Chapter XXVIII: Theætetus (1)

[Side-note: Subjects and personages in the Theætêtus.]

In this dialogue, as in the Parmenides immediately preceding, Plato dwells upon the intellectual operations of mind: introducing the ethical and emotional only in a partial and subordinate way. The main question canvassed is, What is Knowledge--Cognition--Science? After a long debate, turning the question over in many distinct points of view, and examining three or four different answers to the question--all these answers are successively rejected, and the problem remains unsolved.

The two persons who converse with Sokrates are, Theodôrus, an elderly man, eminent as a geometrician, astronomer, &c., and teaching those sciences--and Theætêtus, a young man of great merit and still greater promise: acute, intelligent, and inquisitive--high-principled and courageous in the field, yet gentle and conciliatory to all: lastly, resembling Sokrates in physiognomy and in the flatness of his nose. The dialogue is supposed to have taken place during the last weeks of the life of Sokrates, when his legal appearance as defendant is required to answer the indictment of Melêtus, already entered in the official record.[1] The dialogue is here read aloud to Eukleides of Megara and his fellow-citizen Terpsion, by a slave of Eukleides: this last person had recorded it in writing from narrative previously made to him by Sokrates.[2] It is prefaced by a short discourse between Eukleides and Terpsion, intended to attract our sympathy and admiration towards the youthful Theætêtus.

[Footnote 1: Plato, Theætêt. ad fin. p. 210.]

[Footnote 2: Plato, Theætêt. i. pp. 142 E, 143 A. Plato hardly keeps up the fiction about the time of this dialogue with perfect consistency. When it took place, the indictment of Melêtus had already been recorded: Sokrates breaks off the conversation for the purpose of going to answer it: Eukleides hears the dialogue from the mouth of Sokrates afterwards. "Immediately on getting home to Megara" (says Eukleides) "I wrote down memoranda (of what I had heard): then afterwards I called it back to my mind at leisure, and as often as I visited Athens I questioned Sokrates about such portions as I did not remember, and made corrections on my return here, so that now nearly all the dialogue has been written out."

Such a process would require longer time than is consistent with the short remainder of the life of Sokrates. Socher indeed tries to explain this by assuming a long interval between the indictment and the trial, but this is noway satisfactory. (Ueber Platon's Schriften, p. 251.)

Mr. Lewis Campbell, in the Preface to his very useful edition of this dialogue (p. lxxi. Oxford, 1861), considers that the battle in which Theætêtus is represented as having been wounded, is probably meant for that battle in which Iphikrates and his peltasts destroyed the Spartan Mora, B.C. 390: if not that, then the battle at the Isthmus of Corinth against Epaminondas. B.C. 369. Schleiermacher in his Einleitung to the dialogue (p. 185) seems to prefer the supposition of some earlier battle or skirmish under Iphikrates. The point can hardly be determined. Still less can we fix the date at which the dialogue was written, though the mention of the battle of Corinth certifies that it was later than 394 B.C. Ast affirms confidently that it was the first dialogue composed by Plato after the Phædon, which last was composed immediately after the death of Sokrates (Ast, Platon's Leben, &c., p. 192). I see no ground for this affirmation. Most of the commentators rank it among the dialectical dialogues, which they consider to belong to a later period of Plato's life than the ethical, but to an earlier period than the constructive, such as Republic, Timæus, &c. Most of them place the Theætêtus in one or other of the years between 393-383 B.C., though they differ much among themselves whether it is to be considered as later or earlier than other dialogues--Kratylus, Euthydemus, Menon, Gorgias, &c. (Stallbaum, Proleg. Theæt. pp. 6-10; Steinhart, Einleit. zum Theæt. pp. 100-213.) Munk and Ueberweg, on the contrary, place the Theætêtus at a date considerably later, subsequent to 368 B.C. Munk assigns it to 358 or 357 B.C. after Plato's last return from Sicily (Munk, Die natürliche Ordnung der Platon. Schr. pp. 357-597: Ueberweg, Ueber die Aechtheit der Platon. Schr. pp. 228-236).]

[Side-note: Question raised by Sokrates--What is knowledge or Cognition? First answer of Theætêtus, enumerating many different cognitions. Corrected by Sokrates.]

In answer to the question put by Sokrates--What is Knowledge or Cognition? Theætêtus at first replies--That there are many and diverse cognitions:--of geometry, of arithmetic, of arts and trades, such as shoemaking, joinery, &c. Sokrates points out (as in the Menon, Hippias Major, and other dialogues) that such an answer involves a misconception of the question: which was general, and required a general answer, setting forth the characteristic common to all cognitions. No one can know what cognition is in shoemaking or any particular case--unless he first knows what is cognition generally.[3] Specimens of suitable answers to general questions are then given (or of definition of a general term), in the case of clay--and of numbers square and oblong.[4] I have already observed more than once how important an object it was with Plato to impress upon his readers an exact and adequate conception of the meaning of general terms, and the proper way of defining them. For this purpose he brings into contrast the misconceptions likely to arise in the minds of persons not accustomed to dialectic.

[Footnote 3: Plato, Theætêt. p. 147 A.

[Greek: Ou)d' a)/ra e)pistê/mên u(podêma/tôn suni/êsin, o( e)pistê/mên mê\ ei)dio/s? Ou) ga/r.]]

[Footnote 4: Plato, Theætêt. p. 148. Oblong ([Greek: promê/keis]) numbers are such as can be produced only from two unequal factors. The explanation of this difficult passage, requiring us to keep in mind the geometrical conception of numbers usual among the Greek mathematicians, will be found clearly given in Mr. Campbell's edition of this dialogue, pp. 20-22.]

[Side-note: Preliminary conversation before the second answer is given. Sokrates describes his own peculiar efficacy--mental obstetric--He cannot teach, but he can evolve knowledge out of pregnant minds.]

Theætêtus, before he attempts a second answer, complains how much the subject had embarrassed him. Impressed with what he had heard about the interrogatories of Sokrates, he had tried to solve this problem: but he had not been able to satisfy himself with any attempted solution--nor yet to relinquish the search altogether. "You are in distress, Theætêtus" (observes Sokrates), "because you are not empty, but pregnant.[5] You have that within you, of which you need to be relieved; and you cannot be relieved without obstetric aid. It is my peculiar gift from the Gods to afford such aid, and to stimulate the parturition of pregnant minds which cannot of themselves bring forth what is within them.[6] I can produce no truth myself: but I can, by my art inherited from my mother the midwife Phænaretê, extract truth from others, and test the answers given by others: so as to determine whether such answers are true and valuable, or false and worthless. I can teach nothing: I only bring out what is already struggling in the minds of youth: and if there be nothing within them, my procedure is unavailing. My most important function is, to test the answers given, how far they are true or false. But most people, not comprehending my drift, complain of me as a most eccentric person, who only makes others sceptical. They reproach me, and that truly enough, with always asking questions, and never saying any thing of my own: because I have nothing to say worth hearing.[7] The young companions who frequent my society, often suffer long-continued pains of parturition night and day, before they can be delivered of what is within them. Some, though apparently stupid when they first come to me, make great progress, if my divine coadjutor is favourable to them: others again become tired of me, and go away too soon, so that the little good which I have done them becomes effaced. Occasionally, some of these impatient companions wish to return to me afterwards--but my divine sign forbids me to receive them: where such obstacle does not intervene, they begin again to make progress."[8]

[Footnote 5: Plato, Theætêt. p. 148 E. [Greek: ô)di/neis, dia\ to\ mê\ keno\s a)ll' e)gku/môn ei)=nai.]]

[Footnote 6: Plato, Theætêt. p. 149 A, p. 150 A.]

[Footnote 7: Plato, Theætêt. p. 149 A. [Greek: oi( de/, a)/te ou)k ei)do/tes, tou=to me\n ou) le/gousi peri\ e)mou=, o(/ti de\ a)topô/tato/s ei)mi, kai\ poiô= tou\s a)nthrô/pous a)porei=n.] 150 B-C [Greek: me/giston de\ tou=t' e(/ni tê=| ê(mete/ra| te/chnê|, basani/zein dunato\n ei)=nai panti\ tro/pô|, po/teron ei)/dôlon ê)\ pseu=dos a)poti/ktei tou= ne/ou ê( dianoi/a, ê)\ go/nimo/n te kai\ a)lêthe/s; e)pei\ to/de ge kai\ e)moi\ u(pa/rchei o(/per tai=s mai/ais; a)/gono/s ei)mi sophi/as], &c.]

[Footnote 8: Plato, Theætêt. pp. 150 E, 151 A. [Greek: e)ni/ois me\n to\ gigno/meno/n moi daimo/nion a)pokôlu/ei xunei=nai, e)ni/ois de\ e)a=|; kai\ pa/lin ou(=toi e)pidido/asin.]

We here see (what I have already adverted to in reviewing the Theagês, vol. ii. ch. xv. pp. 105-7) the character of mystery, unaccountable and unpredictable in its working on individuals, with which Plato invests the colloquy of Sokrates.]

[Side-note: Ethical basis of the cross-examination of Sokrates--He is forbidden to pass by falsehood without challenge.]

This passage, while it forcibly depicts the peculiar intellectual gift of Sokrates, illustrates at the same time the Platonic manner of describing, full of poetry and metaphor. Cross-examination by Sokrates communicated nothing new, but brought out what lay buried in the mind of the respondent, and tested the value of his answers. It was applicable only to minds endowed and productive: but for them it was indispensable, in order to extract what they were capable of producing, and to test its value when extracted. "Do not think me unkind," (says Sokrates,) "or my procedure useless, if my scrutiny exposes your answers as fallacious. Many respondents have been violently angry with me for doing so: but I feel myself strictly forbidden either to admit falsehood, or to put aside truth."[9] Here we have a suitable prelude to a dialogue in which four successive answers are sifted and rejected, without reaching, even at last, any satisfactory solution.

[Footnote 9: Plato, Theætêt. p. 151 D.]

[Side-note: Answer of Theætêtus--Cognition is sensible perception: Sokrates says that this is the same doctrine as the _Homo Mensura_ laid down by Protagoras, and that both are in close affinity with the doctrines of Homer, Herakleitus, Empedoklês, &c., all except Parmenides.]

The first answer given by Theætêtus is--"Cognition is sensation (or sensible perception)". Upon this answer Sokrates remarks, that it is the same doctrine, though in other words, as what was laid down by Protagoras--"Man is the measure of all things: of things existent, that they exist: of things non-existent, that they do not exist. As things appear to me, so they are to me: as they appear to you, so they are to you."[10] Sokrates then proceeds to say, that these two opinions are akin to, or identical with, the general view of nature entertained by Herakleitus, Empedoklês, and other philosophers, countenanced moreover by poets like Homer and Epicharmus. The philosophers here noticed (he continues), though differing much in other respects, all held the doctrine that nature consisted in a perpetual motion, change, or flux: that there was no real Ens or permanent substratum, but perpetual genesis or transition.[11] These philosophers were opposed to Parmenides, who maintained (as I have already stated in a previous chapter) that there was nothing real except Ens--One, permanent, and unchangeable: that all change was unreal, apparent, illusory, not capable of being certainly known, but only matter of uncertain opinion or estimation.

[Footnote 10: Plato, Theætêt. pp. 151 E--152 A.

_Theætêt._ [Greek: ou)k a)/llo ti/ e)stin e)pistê/mê ê)\ ai)/sthêsis. . . .]

_Sokrat._ [Greek: Kinduneu/eis me/ntoi lo/gon ou) phau=lon ei)rêke/nai peri\ e)pistê/mês, a)ll' o(/n e)/lege kai\ Prôtago/ras; _tro/pon de/ tina a)/llon ei)/rêke ta\ au)ta\ tau=ta. Phêsi\ ga/r pou--Pa/ntôn chrêma/tôn me/tron a)/nthrôpon ei)=nai, tô=n me\n o)/ntôn, ô(s e)/sti--tô=n de\ mê\ o)/ntôn, ô(s ou)k e)/stin._ A)ne/gnôkas ga/r pou?]

_Theætêt._ [Greek: A)ne/gnôka kai\ polla/kis.]

_Sokrat._ [Greek: Ou)kou=n ou(/tô pôs le/gei, ôs oi(=a me\n e(/kasta e)moi\ phai/netai, toiau=ta me/n e)stin e)moi\--oi(=a de\ soi/, toiau=ta de\ au)= soi/; a)nthrôpos de\ su/ te ka)gô/.]

_Theætêt._ [Greek: Le/gei ga\r ou)=n ou(/tôs.]

Here Plato appears to transcribe the words of Protagoras (compare p. 161 B, and the Kratylus, p. 386 A) which distinctly affirm the doctrine of _Homo Mensura_--Man is the measure of all things,--but do not affirm the doctrine, that knowledge is sensible perception. The identification between the two doctrines is asserted by Plato himself. It is Plato who asserts "that Protagoras affirmed the same doctrine in another manner," citing afterwards the manner in which he supposed Protagoras to affirm it. If there had been in the treatise of Protagoras any more express or peremptory affirmation of the doctrine "that knowledge is sensible perception," Plato would probably have given it here.]

[Footnote 11: Plato, Theætêt. p. 152 E. [Greek: kai\ peri\ tou/tou _pa/ntes e(xê=s oi( sophoi\ plê\n Parmeni/dou xumphere/sthôn_, Prôtago/ras te kai\ Ê(ra/kleitos kai\ E)mpedoklê=s, kai\ tô=n poiêtô=n oi( a)/kroi tê=s poiê/seôs e(kate/ras, kômô|di/as me\n E)pi/charmos, tragô|di/as de\ O(/mêros.]]

[Side-note: Plato here blends together three distinct theories for the purpose of confuting them; yet he also professes to urge what can be said in favour of them. Difficulty of following his exposition.]

The one main theme intended for examination here (as Sokrates[12] expressly declares) is the doctrine--That Cognition is sensible perception. Nevertheless upon all the three opinions, thus represented as cognate or identical,[13] Sokrates bestows a lengthened comment (occupying a half of the dialogue) in conversation, principally with Theætêtus, but partly also with Theodôrus. His strictures are not always easy to follow with assurance, because he often passes with little notice from one to the other of the three doctrines which he is examining: because he himself, though really opposed to them, affects in part to take them up and to suggest arguments in their favour: and further because, disclaiming all positive opinion of his own, he sometimes leaves us in doubt what is his real purpose--whether to expound, or to deride, the opinions of others--whether to enlighten Theætêtus, or to test his power of detecting fallacies.[14] We cannot always distinguish between the ironical and the serious. Lastly, it is a still greater difficulty, that we have not before us either of the three opinions as set forth by their proper supporters. There remains no work either of Protagoras or of Herakleitus: so that we do not clearly know the subject matter upon which Plato is commenting--nor whether these authors would have admitted as just the view which he takes of their opinions.[15]

[Footnote 12: Plato, Theætêt. p. 163 A.]

[Footnote 13: Plato, Theætêt. p. 160 D. _Sokrat._ [Greek: Pagka/lôs a)/ra soi ei)/rêtai o(/ti e)pistê/mê ou)k a)/llo ti/ e)stin ê)\ ai)/sthêsis; kai\ _ei)s tau)to\n sumpe/ptôke_, kata\ me\n O(/mêron kai\ Ê(ra/kleiton kai\ pa=n to\ toiou=ton phu=lon, oi(=on r(eu/mata kinei=sthai ta\ pa/nta--kata\ de\ Prôtago/ran to\n sophô/taton, pa/ntôn chrêma/tôn a)/nthrôpon me/tron ei)=nai--kata\ de\ Theai/têton, tou/tôn ou(=tôs e)cho/ntôn, ai)/sthêsin e)pistê/mên gi/gnesthai.]]

[Footnote 14: See the answer of Theætêtus and the words of Sokrates following, p. 157 C.]

[Footnote 15: It would be hardly necessary to remark, that when Plato professes to put a pleading into the mouth of Protagoras (pp. 165-166) we have no other real speaker than Plato himself, if commentators did not often forget this. Steinhart indeed tells us (Einleit. zum Theætêt. pp. 36-47) positively--that Plato in this pleading keeps in the most accurate manner (auf das genaueste) to the thoughts of Protagoras, perhaps even to his words. How Steinhart can know this I am at a loss to understand. To me it seems very improbable. The mere circumstance that Plato forces into partnership three distinct theories, makes it probable that he did not adhere to the thoughts or language of any one of them.]

[Side-note: The doctrine of Protagoras is completely distinct from the other doctrines. The identification of them as one and the same is only constructive--the interpretation of Plato himself.]

It is not improbable that the three doctrines, here put together by Plato and subjected to a common scrutiny, may have been sometimes held by the same philosophers. Nevertheless, the language[16] of Plato himself shows us that Protagoras never expressly affirmed knowledge to be sensible Perception: and that the substantial identity between this doctrine, and the different doctrine maintained by Protagoras, is to be regarded as a construction put upon the two by Plato. That the theories of Herakleitus and Empedokles differed materially from each other, we know certainly: the theory of each, moreover, differed from the doctrine of Protagoras--"Man is the measure of all things". How this last doctrine was defended by its promulgator, we cannot say. But the defence of it noway required him to maintain--That knowledge is sensible perception. It might be consistently held by one who rejected that definition of knowledge.[17] And though Plato tries to refute both, yet the reasonings which he brings against one do not at all tell against the other.

[Footnote 16: See Theætêt. p. 152 A. This is admitted (to be a construction put by Plato himself) by Steinhart in his note 7, p. 214, Einleitung zum Theætêtus, though he says that Plato's construction is the right one.]

[Footnote 17: Dr. Routh, in a note upon his edition of the Euthydêmus of Plato (p. 286 C) observes:--"Protagoras docebat, [Greek: Pa/ntôn chrêma/tôn me/tron a)/nthrôpon ei)=nai, tô=n me\n o)/ntôn, ô(s e)/sti; tô=n de\ mê\ o)/ntôn, ô(s ou)k e)/sti.] Quâ quidem opinione qualitatum sensilium sine animi perceptione existentiam sustulisse videtur."

The definition here given by Routh is correct as far as it goes, though too narrow. But it is sufficient to exhibit the Protagorean doctrine as quite distinct from the other doctrine, [Greek: o(/ti e)pistê/mê ou)k a)/llo ti/ e)stin ê)\ ai)/sthêsis.]]

[Side-note: Explanation of the doctrine of Protagoras--_Homo Mensura_.]

The Protagorean doctrine--Man is the measure of all things--is simply the presentation in complete view of a common fact--uncovering an aspect of it which the received phraseology hides. Truth and Falsehood have reference to some believing subject--and the words have no meaning except in that relation. Protagoras brings to view this subjective side of the same complex fact, of which Truth and Falsehood denote the objective side. He refuses to admit the object absolute--the pretended _thing in itself_--Truth without a believer. His doctrine maintains the indefeasible and necessary involution of the percipient mind in every perception--of the concipient mind in every conception--of the cognizant mind in every cognition. Farther, Protagoras acknowledges many distinct believing or knowing Subjects: and affirms that every object known must be relative to (or in his language, _measured by_) the knowing Subject: that every _cognitum_ must have its _cognoscens_, and every _cognoscibile_ its _cognitionis capax_: that the words have no meaning unless this be supposed: that these two names designate two opposite poles or aspects of the indivisible fact of cognition--actual or potential--not two factors, which are in themselves separate or separable, and which come together to make a compound product. A man cannot in any case get clear of or discard his own mind as a Subject. Self is necessarily omnipresent; concerned in every moment of consciousness, and equally concerned in all, though more distinctly attended to in some than in others.[18] The Subject, self, or Ego, is that which all our moments of consciousness have in common and alike: Object is that in which they do or may differ--although some object or other there always must be. The position laid down by Descartes--_Cogito, ergo sum_--might have been stated with equal truth--_Cogito, ergo est (cogitatum aliquid)_: _sum cogitans--est cogitatum_--are two opposite aspects of the same indivisible mental fact--_cogitatio_. In some cases, doubtless, the objective aspect may absorb our attention, eclipsing the subjective: in other cases, the subjective attracts exclusive notice: but in all cases and in every act of consciousness, both are involved as co-existent and correlative. That alone exists, to every man, which stands, or is believed by him to be capable of standing, in some mode of his consciousness as an Object correlative with himself as a Subject. If he believes in its existence, his own believing mind is part and parcel of such fact of belief, not less than the object believed in: if he disbelieves it, his own disbelieving mind is the like. Consciousness in all varieties has for its two poles Subject and Object: there cannot be one of these poles without the opposite pole--north without south--any more than there can be concave without convex (to use a comparison familiar with Aristotle), or front without back: which are not two things originally different and coming into conjunction, but two different aspects of the same indivisible fact.

[Footnote 18: In regard to the impossibility of carrying abstraction so far as to discard the thinking subject, see Hobbes, Computation or Logic, ch. vii. 1.

"In the teaching of natural philosophy I cannot begin better than from _privation_; that is, from feigning the world to be annihilated. But if such annihilation of all things be supposed, it may perhaps be asked what would remain for any man (_whom only I except from this universal annihilation of things_) to consider as the subject of philosophy, or at all to reason upon; or what to give names unto for ratiocination's sake.

"I say, therefore, there would remain to that man ideas of the world, and of all such bodies as he had, before their annihilation, seen with his eyes, or perceived by any other sense; that is to say, the memory and imagination of magnitudes, motions, sounds, colours, &c., as also of their order and parts. All which things, though they be nothing but ideas and phantasms, happening internally to him that imagineth, yet they will appear as if they were external and not at all depending upon any power of the mind. And these are the things to which he would give names and subtract them from, and compound them with one another. For seeing that after the destruction of all other things I suppose man still remaining, and namely that he thinks, imagines, and remembers, there can be nothing for him to think of but what is past. . . . Now things may be considered, that is, be brought into account, _either as internal accidents of our mind_, in which manner we consider them when the question is about _some faculty of the mind_: or, as _species of external things, not as really existing, but appearing only to exist, or to have a being without us_. And in this manner we are now to consider them."]

[Side-note: Perpetual implication of Subject with Object--Relate and Correlate.]

In declaring that "Man is the measure of all things"--Protagoras affirms that Subject is the measure of Object, or that every object is relative to a correlative Subject. When a man affirms, believes, or conceives, an object as existing, his own believing or concipient mind is one side of the entire fact. It may be the dark side, and what is called _the Object_ may be the light side, of the entire fact: this is what happens in the case of tangible and resisting substances, where Object, being the light side of the fact, is apt to appear all in all:[19] a man thinks of the Something which resists, without attending to the other aspect of the fact of resistance, _viz._: his own energy or pressure, to which resistance is made. On the other hand, when we speak of enjoying any pleasure or suffering any pain, the enjoying or suffering Subject appears all in all, distinguished plainly from other Subjects, supposed to be not enjoying or suffering in the same way: yet it is no more than the light side of the fact, of which Object is the dark side. Each particular pain which we suffer has its objective or differential peculiarity, distinguishing it from other sensations, correlating with the same sentient Subject.

[Footnote 19: "Nobiscum semper est ipsa quam quærimus (anima); adest, tractat, loquitur--et, si fas est dicere, inter ista nescitur." (Cassiodorus, De Animâ, c. 1, p. 594, in the edition of his Opera Omnia, Venet. 1729).

"In the primitive dualism of consciousness, the Subject and Object being inseparable, either of them apart from the other must be an unknown quantity: the separation of either must be the annihilation of both." (F. W. Farrar, Chapters on Language, c. 23, p. 292: which chapter contains more on the same topic, well deserving of perusal.)]

[Side-note: Such relativity is no less true in regard to the ratiocinative combinations of each individual, than in regard to his percipient capacities.]

The Protagorean dictum will thus be seen, when interpreted correctly, to be quite distinct from that other doctrine with which Plato identifies it: that Cognition is nothing else but sensible Perception. If, rejecting this last doctrine, we hold that cognition includes mental elements distinct from, though co-operating with, sensible perception--the principle of relativity laid down by Protagoras will not be the less true. My intellectual activity--my powers of remembering, imagining, ratiocinating, combining, &c., are a part of my mental nature, no less than my powers of sensible perception: my cognitions and beliefs must all be determined by, or relative to, this mental nature: to the turn and development which all these various powers have taken in my individual case. However multifarious the mental activities may be, each man has his own peculiar allotment and manifestations thereof, to which his cognitions must be relative. Let us grant (with Plato) that the Nous or intelligent Mind apprehends intelligible Entia or Ideas distinct from the world of sense: or let us assume that Kant and Reid in the eighteenth century, and M. Cousin with other French writers in the nineteenth, have destroyed the Lockian philosophy, which took account (they say) of nothing but the _à posteriori_ element of cognition--and have established the existence of other elements of cognition _à priori_: intuitive beliefs, first principles, primary or inexplicable Concepts of Reason.[20] Still we must recollect that all such _à priori_ Concepts, Intuitions, Beliefs, &c., are summed up in the mind: and that thus each man's mind, with its peculiar endowments, natural or supernatural, is still the measure or limit of his cognitions, acquired and acquirable. The Entia Rationis exist relatively to Ratio, as the Entia Perceptionis exist relatively to Sense. This is a point upon which Plato himself insists, in this very dialogue. You do not, by producing this fact of innate mental intuitions, eliminate the intuent mind; which must be done in order to establish a negative to the Protagorean principle.[21] Each intuitive belief whether correct or erroneous--whether held unanimously by every one _semper et ubique_, or only held by a proportion of mankind--is (or would be, if proved to exist) a fact of our nature; capable of being looked at either on the side of the believing Subject, which is its point of community with all other parts of our nature--or on the side of the Object believed, which is its point of difference or peculiarity. The fact with its two opposite aspects is indivisible. Without Subject, Object vanishes: without Object (some object or other, for this side of the fact is essentially variable), Subject vanishes.

[Footnote 20: See M. Jouffroy, Préface à sa Traduction des OEuvres de Reid, pp. xcvii.-ccxiv.

M. Jouffroy, following in the steps of Kant, declares these _à priori_ beliefs or intuitions to be altogether relative to the human mind. "Kant, considérant que les conceptions de la raison sont des croyances aveugles auxquelles notre esprit se sent fatalement déterminé par sa nature, en conclut qu'elles sont rélatives à cette nature: que si notre nature était autre, elles pourraient être différentes: que par conséquent, elles n'ont aucune valeur absolue: et qu'ainsi notre vérité, notre science, notre certitude, sont une vérité, une science, une certitude, purement _subjective_, purement humaine--à laquelle nous sommes déterminés à nous fier par notre nature, mais qui ne supporte pas l'examen et n'a aucune valeur _objective_" (p. clxvii.) . . . "C'est ce que répéte Kant quand il soutient que l'on ne peut _objectiver le subjectif_: c'est à dire, faire que la vérité humaine cesse d'être humaine, puisque la raison qui la trouve est humaine. On peut exprimer de vingt manières différentes cette impossibilité: elle reste toujours la même, et demeure toujours insurmontable," p. cxc. Compare p. xcvii. of the same Preface.

M. Pascal Galuppi (in his Lettres Philosophiques sur les Vicissitudes de la Philosophie, translated from the Italian by M. Peisse, Paris, 1844) though not agreeing in this variety of _à priori_ philosophy, agrees with Kant in declaring the _à priori_ element of cognition to be purely subjective, and the objective element to be _à posteriori_ (Lett. xiv. pp. 337-338), or the facts of sense and experience. "L'ordre _à priori_, que Kant appelle _transcendental_, est purement idéal, et dépourvu de toute réalité. Je vis, qu'en fondant la connaissance sur l'ordre _à priori_, on arrive nécessairement au scepticisme: et je reconnus que la doctrine Écossaise est la mère légitime du Criticisme Kantien, et par conséquent, du scepticisme, qui est la conséquence de la philosophie critique. Je considérai comme de haute importance ce problème de Kant. Il convient de déterminer ce qu'il y a d'objectif, et ce qu'il y a de subjectif, dans la connaissance. Les Empiriques n'admettent dans la connaissance d'autres élémens que les objectifs," &c.]

[Footnote 21: See this point handled in Sextus Empiric. adv. Mathemat. viii. 355-362. We may here cite a remark of Simplikius in his Commentary on the Categories of Aristotle (p. 64, a. in Schol. Brandis). Aristotle (De Animâ, iii. 2, 426, a. 19; Categor. p. 7, b. 23) lays down the doctrine that in most cases Relata or ([Greek: ta\ pro/s ti]) are "simul Naturâ, [Greek: kai\ sunanairei= a)/llêla]": but that in some Relata this is not true: for example, [Greek: to\ e)pistêto\n] is relative to [Greek: e)pistê/mê], yet still _it would seem prior_ to [Greek: e)pistê/mê (pro/teron a)\n do/xeie tê=s e)pistê/mês ei)=nai)]. There cannot be [Greek: e)pistê/mê] without some [Greek: e)pistêto/n]: but there may be [Greek: e)pistêto\n] without any [Greek: e)pistê/mê]. There are few things, if any (he says), in which the [Greek: e)pistêto\n] (cognoscibile) is _simul naturâ_ with [Greek: e)pistê/mê] (or cognitio) and cannot be without it.

Upon which Simplikius remarks, What are these few things? [Greek: Ti/na de\ ta\ o)li/ga e)sti/n, e)ph' ô(=n a(/ma tô=| e)pistêtô=| ê( e)pistê/mê e)sti/n? Ta\ a)/neu u(/lês, ta\ noêta/, a(/ma tô=| kat' e)nergei/an a)ei\ e)stô/sê| e)pistê/mê e)/stin, ei)/te kai\ e)n ê(mi=n e)sti/ tis toiau/tê a)ei\ a)/nô me/nousa, . . . ei)/te kai\ e)n tô=| kat' e)nergei/an vô=| ei)/ tis kai\ tê\n no/êsin e)kei/nên e)pistê/mên e(/loito kalei=n. du/natai de\ kai\ dia\ tê\n tô=n koinô=n u(po/stasin ei)rê=sthai, tê\n e)x a)phaire/seôs; a(/ma ga\r tê=| u(posta/sei tou/tôn kai\ ê( e)pistê/mê e)sti/n. a)lêthe\s de\ kai\ e)pi\ tô=n a)naplasma/tôn tô=n te e)n tê=| phantasi/a| kai\ tô=n technitô=n; a(/ma ga\r chi/maira kai\ ê( e)pistê/mê chimai/ras.]

We see from hence that Simplikius recognises Concepts, Abstractions, and Fictions, to be dependent on the Conceiving, Abstracting, Imagining, Mind--as distinguished from objects of Sense, which he does not recognise as dependent in the like manner. He agrees in the doctrine of Protagoras as to the former, but not as to the latter. This illustrates what I have affirmed, That the Protagorean doctrine of "_Homo Mensura_" is not only unconnected with the other principle (that Knowledge is resolvable into sensible perception) to which Aristotle and Plato would trace it--but that there is rather a repugnance between the two. The difficulty of proving the doctrine, and the reluctance to admit it, is greatest in the case of material objects, least in the case of Abstractions, and General Ideas. Yet Aristotle, in reasoning against the Protagorean doctrine (Metaphysic. [Greek: G]. pp. 1009-1010, &c.) treats it like Plato, as a sort of corollary from the theory that Cognition is Sensible Perception.

Simplikius farther observes (p. 65, b. 14) that Aristotle is not accurate in making [Greek: e)pistêto\n] correlate with [Greek: e)pistê/mê]: that in Relata, the potential correlates with the potential, and the actual with the actual. The Cognoscible is correlative, not with actual cognition ([Greek: e)pistê/mê]) but with potential Cognition, or with a potential Cognoscens. Aristotle therefore is right in saying that there may be [Greek: e)pistêto\n] without [Greek: e)pistê/mê], but this does not prove what he wishes to establish.

Themistius, in another passage of the Aristotelian Scholia, reasoning against Boethus, observes to the same effect as Simplikius, that in relatives, the actual correlates with the actual, and the potential with the potential:--

[Greek: Kai/toi, phêsi/ ge o( Boêtho/s, ou)de\n kôlu/ei to\n a)rithmo\n ei)=nai kai\ di/cha tou= a)rithmou=ntos, ô(/sper oi)=mai to\ ai)sthêto\n kai\ di/cha tou= ai)sthanome/nou; spha/lletai de/, a(/ma ga\r ta\ pro\s ti/, kai\ ta\ duna/mei pro\s ta\ duna/mei; ô(/ste ei) mê\ kai\ a)rithmêtiko/n, ou)de\ to\ a)rithmêto/n] (Schol. ad Aristot. Physic. iv. p. 223, a. p. 393, Schol. Brandis).

Compare Aristotel. Metaphysic. M. 1087, a. 15, about [Greek: to\ e)pi/stasthai duna/mei] and [Greek: to\ e)pi/stasthai e)nergei/a|].

About the essential co-existence of relatives--Sublato uno, tollitur alterum--see also Sextus Empiric. adv. Mathematicos, vii. 395, p. 449, Fabric.]

[Side-note: Evidence from Plato proving implication of Subject and Object, in regard to the intelligible world.]

That this general doctrine is true, not merely respecting the facts of sense, but also respecting the facts of mental conception, opinion, intellection, cognition--may be seen by the reasoning of Plato himself in other dialogues. How, for example, does Plato prove, in his Timæus, the objective reality of Ideas or Forms? He infers them from the subjective facts of his own mind. The subjective fact called Cognition (he argues) is generically different from the subjective fact called True Opinion: therefore the Object correlating with the One must be distinct from the Object correlating with the other: there must be a Noumenon or [Greek: noêto/n ti] correlating with Nous, distinct from the [Greek: doxasto/n ti] which correlates with [Greek: do/xa].[22] So again, in the Phædon,[23] Sokrates proves the pre-existence of the human soul from the fact that there were pre-existent cognizable Ideas: if there were knowable Objects, there must also have been a Subject Cognoscens or Cognitionis capax. The two are different aspects of one and the same conception: upon which we may doubtless reason abstractedly under one aspect or under the other, though they cannot be separated in fact. Now Both these two inferences of Plato rest on the assumed implication of Subject and Object.[24]

[Footnote 22: Plato, Timæus, p. 51 B-E, compare Republic, v. p. 477.

See this reasoning of Plato set forth in Zeller, Die Phil. der Griech. vol. ii. pp. 412-416, ed. 2nd.

_Nous_, according to Plato (Tim. 51 E), belongs only to the Gods and to a select few among mankind. It is therefore only _to_ the Gods and _to_ these few men that [Greek: Noêta\] exist. To the rest of mankind [Greek: Noêta\] are non-apparent and non-existent.]

[Footnote 23: Plato, Phædon, pp. 76-77. [Greek: i)/sê a)na/gkê tau=ta/ te] (Ideas or Forms) [Greek: ei)=nai, kai\ ta\s ê(mete/ras psucha\s pri\n kai\ ê(ma=s gegone/nai--kai\ ei) mê\ tau=ta, ou)de\ ta/de. U(perphuô=s, e)/phê o( Simmi/as, dokei= moi ê( au)tê\ a)na/gkê ei)=nai, kai\ ei)s kalo/n ge katapheu/gei o( lo/gos ei)s to\ o(moi/ôs ei)=nai tê/n te psuchê\n ê(mô=n pri\n gene/sthai ê(ma=s kai\ tê\n ou)si/an ê(\n su\ nu=n le/geis.]

Compare p. 92 E of the same dialogue with the notes of Wyttenbach and Heindorf--"Haec autem [Greek: ou)si/a] Idearum, rerum intelligibilium, [Greek: au)tê=s e)sti\n] (_sc._ [Greek: tê=s psuchê=s]) ut hoc loco dicitur, est propria et possessio animæ nostræ," &c.

About the essential implication of [Greek: Nou=s] with the [Greek: Noêta/], as well as of [Greek: to\ do/xazon] with [Greek: ta\ doxazo/mena], and of [Greek: to\ ai)sthano/menon] with [Greek: ta\ ai)sthêta/], see Plutarch, De Animæ Procreat. in Timæo, pp. 1012-1024; and a curious passage from Joannes Philoponus ad Aristot. Physica, cited by Karsten in his Commentatio De Empedoclis Philosophiâ, p. 372, and Olympiodorus ad Platon. Phædon, p. 21. [Greek: to\n nou=n phame\n a)kribô=s ginô/skein, dio/ti au)to/s e)sti to\ noêto/n.]

Sydenham observes, in a note upon his translation of the Philêbus (note 76, p. 118), "Being Intelligent and Being Intelligible are not only correlatives, but are so in their very essence: neither of them can be at all, without the Being of the other".]

[Footnote 24: I think that the inference in the Phædon is not necessary to prove that conclusion, nor in itself just. For when I speak of Augustus and Antony as having once lived, and as having fought the battle of Actium, it is noway necessary that I should believe myself to have been then alive and to have seen them: nor when I speak of civil war as being now carried on in the United States of America, is it necessary that I should believe myself to be or to have been on the spot as a percipient witness. I believe, on evidence which appears to me satisfactory, that both these are real facts: that is, if I had been at Actium on the day of the battle, or if I were now in the United States, I should see and witness the facts here affirmed. These latter words describe the subjective side of the fact, without introducing any supposition that I have been myself present and percipient.]

[Side-note: The Protagorean measure is even more easily shown in reference to the intelligible world than in reference to sense.]

In truth, the Protagorean measure or limit is even more plainly applicable to our mental intuitions and mental processes (remembering, imagining, conceiving, comparing, abstracting, combining of hypotheses, transcendental or inductive) than to the matter of our sensible experience.[25] In regard to the Entia Rationis, divergence between one theorist and another is quite as remarkable as the divergence between one percipient and another in the most disputable region of Entia Perceptionis. Upon the separate facts of sense, there is a nearer approach to unanimity among mankind, than upon the theories whereby theorising men connect together those facts to their own satisfaction. An opponent of Protagoras would draw his most plausible arguments from the undisputed facts of sense. He would appeal to matter and what are called its primary qualities, as refuting the doctrine. For in describing mental intuitions, Mind or Subject cannot well be overlaid or ignored: but in regard to the external world, or material substance with its primary qualities, the objective side is so lighted up and magnified in the ordinary conception and language--and the subjective side so darkened and put out of sight--that Object appears as if it stood single, apart, and independent.

[Footnote 25: Bacon remarks that the processes called mental or intellectual are quite as much relative to man as those called sensational or perceptive. "Idola Tribûs sunt fundata in ipsâ naturâ humanâ. Falso enim asseritur, Sensum humanum esse mensuram rerum: quin contra, omnes perceptiones, tam Sensûs quam Mentis, sunt ex analogiâ hominis, non ex analogiâ Universi."

Nemesius, the Christian Platonist, has a remark bearing upon this question. He says that the lower animals have their intellectual movements all determined by Nature, which acts alike in all the individuals of the species, but that the human intellect is not wholly determined by Nature; it has a freer range, larger stores of ideas, and more varied combinations: hence its manifestations are not the same in all, but different in different individuals--[Greek: e)leu/theron ga/r ti kai\ au)texou/sion to\ logiko/n, o(/then ou)ch e(\n kai\ tau)to\n pa=sin e)/rgon a)nthrô/pois, ô(s e(ka/stô| ei)/dei tô=n a)lo/gôn zô/ôn; phu/sei ga\r mo/nê| ta\ toiau=ta kinei=tai, ta\ de\ phu/sei o(moi/ôs para\ pa=si/n e)stin; ai( de\ logikai\ pra/xeis a)/llai par' a)/llois kai\ ou)k e)x a)na/gkês ai( au(=tai para\ pa=sin] (De Nat. Hom., c. ii. p. 53. ed. 1565).]

A man conceives objects, like houses and trees, as existing when he does not actually see or touch them, just as much as when he does see or touch them. He conceives them as existing independent of any actual sensations of his own: and he proceeds to describe them as independent altogether of himself as a Subject--or as absolute, not relative, existences. But this distinction, though just as applied in ordinary usage, becomes inadmissable when brought to contradict the Protagorean doctrine; because the speaker professes to exclude, what cannot be excluded, himself as concipient Subject.[26] It is he who conceives absent objects as real and existing, though he neither sees nor touches them: he believes fully, that if he were in a certain position near them, he would experience those appropriate sensations of sight and touch, whereby they are identified. Though he eliminates himself as a _percipient_, he cannot eliminate himself as a _concipient_: _i.e._, as conceiving and believing. He can conceive no object without being himself the Subject conceiving, nor believe in any future contingency without being himself the Subject believing. He may part company with himself as percipient, but he cannot part company with himself altogether. His conception of an absent external object, therefore, when fully and accurately described, does not contradict the Protagorean doctrine. But it is far the most plausible objection which can be brought against that doctrine, and it is an objection deduced from the facts or cognitions of sense.

[Footnote 26: Bishop Berkeley observes:--

"But, say you, surely there is nothing easier than to imagine trees, for instance, in a park, or books existing in a closet, and nobody by to perceive them. I answer, you may so--there is no difficulty in it. But what is all this, more than framing in your mind certain ideas which you call _books_ and _trees_, and at the same time omitting to frame the idea of any one that may perceive them? _But do not you yourself perceive or think of them all the while?_ This therefore is nothing to the purpose. It only shows you have the power of imagining or forming ideas in your mind: but it doth not show that you can conceive it possible the objects of your thought may exist without the mind. _To make out this, it is necessary that you conceive them existing unconceived or unthought of, which is a manifest repugnancy._ When we do our utmost to conceive the existence of external bodies, we are all the while only contemplating our own ideas. _But the mind, taking no notice of itself, is deluded to think it can and doth conceive bodies existing unthought of or without the mind, though at the same time they are apprehended by or exist in itself._"

Berkeley, Principles of Human Knowledge, sect. xxiii. p. 34, ed. of Berkeley's Works, 1820. The same argument is enforced in Berkeley's First Dialogue between Hylas and Philonous, pp. 145-146 of the same volume.

I subjoin a passage from the work of Professor Bain on Psychology, where this difficult subject is carefully analysed (The Senses and the Intellect, p. 370). "There is no possible knowledge of the world except in reference to our minds. Knowledge means a state of mind: the knowledge of material things is a mental thing. We are incapable of discussing the existence of an independent material world: the very act is a contradiction. We can speak only of a world presented to our own minds. By an illusion of language we fancy that we are capable of contemplating a world which does not enter into our own mental existence: but the attempt belies itself, for this contemplation is an effort of mind."

"Solidity, extension, space--the foundation properties of the material world--mean, as has been said above, certain movements and energies of our own bodies, and exist in our minds in the shape of feelings of force, allied with visible and tactile, and other sensible impressions. The sense of the external is the consciousness of particular energies and activities of our own."

(P. 376). "We seem to have no better way of assuring ourselves and all mankind, that with the conscious movement of opening the eyes there will always be a consciousness of light, than by saying that the light exists as an independent fact, without any eyes to see it. But if we consider the fact fairly we shall see that this assertion errs, not simply in being beyond any evidence that we can have, but also in being a self-contradiction. We are affirming _that_ to have an existence out of our minds, which we cannot know but as in our minds. In words we assert independent existence, while in the very act of doing so we contradict ourselves. Even a possible world implies a possible mind to conceive it, just as much as an actual world implies an actual mind. The mistake of the common modes of expression on this matter is the mistake of supposing the abstractions of the mind to have a separate and independent existence. Instead of looking upon the doctrine of an external and independent world as a generalisation or abstraction grounded on our particular experiences, summing up the past and predicting the future, we have got into the way of maintaining the abstraction to be an independent reality, the foundation, or cause, or origin, of all these experiences."

To the same purpose Mr. Mansel remarks in his Bampton Lectures on "The Limits of Religious Thought," page 52:

"A second characteristic of Consciousness is, that it is only possible in the form of a _relation_. There must be a Subject or person conscious, and an Object or thing of which he is conscious. There can be no consciousness without the union of these two factors; and in that union each exists only as it is related to the other. The subject is a subject only in so far as it is conscious of an object: the object is an object only in so far as it is apprehended by a subject: and the destruction of either is the destruction of consciousness itself. It is thus manifest that a consciousness of the Absolute is equally self-contradictory with that of the Infinite. . . Our whole notion of Existence is necessarily relative, for it is existence as conceived by us. But _Existence_, as we conceive it, is but a name for the several ways in which objects are presented to our consciousness--a general term embracing a variety of relations. . . To assume Absolute Existence as an object of thought is thus to suppose a relation existing when the related terms exist no longer. An object of thought exists, as such, in and through its relation to a thinker; while the Absolute, as such, is independent of all relation."

Dr. Henry More has also a passage asserting the essential correlation on which I am here insisting (Immortality of the Soul, ch. ii. p. 3). And Professor Ferrier, in his Institutes of Metaphysic, has given much valuable elucidation respecting the essential relativity of cognition.

Though this note is already long, I shall venture to add from an eminent German critic--Trendelenburg--a passage which goes to the same point.

"Das Sein ist als die absolute Position erklärt worden. Der Begriff des Seins drücke blos das aus: es werde bei dem einfachen Setzen eines _Was_ sein Bewenden haben. Es hat sich hier die abstracte Vorstellung des Seins nur in eine verwandte Anschauung umgekleidet; denn das Gesetzte steht in dem Raum da; und insofern fordert die absolute Position schon den Begriff des seiendem Etwas, das gesetzt wird. _Fragt man weiter, so ist in der absoluten Position schon derjenige mitgedacht, der da setzt._ Das Sein wird also _nicht unabhängig aus sich selbst bestimmt_, sondern zur Erklärung _ein Verhältniss zu der Thätigkeit des Gedankens herbeigezogen_.

"Aehnlich würde jede von vorn herein versuchte Bestimmung des Denkens ausfallen. Man würde es nur durch einen Bezug zu den Dingen erläutern können, welche in dem Denken Grund und Mass finden. Wir begeben uns daher jeder Erklärung, und setzen eine Vorstellung des Denkens und Seins voraus, in der Hoffnung dass beide mit jedem Schritt der Untersuchung sich in sich selbst bestimmen werden." "Indem wir Denken und Sein unterscheiden, fragen wir, wie ist es möglich, dass sich im Erkennen Denken und Sein vereinigt? _Diese Vereinigung sprechen wir vorläufig als eine Thatsache aus, die das Theoretische wie das Praktische beherrscht._" Trendelenburg, Logische Untersuchungen, sect. 3, pp. 103-104, Berlin, 1840.]

[Side-note: Object always relative to Subject--Either without the other, impossible. Plato admits this in Sophistes.]

I cannot therefore agree with Plato in regarding the Protagorean doctrine--Homo Mensura--as having any dependance upon, or any necessary connection with, the other theory (canvassed in the Theætêtus) which pronounces cognition to be sensible perception. Objects of thought exist in relation to a thinking Subject; as Objects of sight or touch exist in relation to a seeing or touching Subject. And this we shall find Plato himself declaring in the Sophistes (where his Eleatic disputant is introduced as impugning a doctrine substantially the same as that of Plato himself in the Phædon, Timæus, and elsewhere) as well as here in the Theætêtus. In the Sophistes, certain philosophers (called the Friends of Forms or Ideas) are noticed, who admitted that all sensible or perceivable existence ([Greek: ge/nesis]--Fientia) was relative to a (capable) sentient or percipient--but denied the relativity of Ideas, and maintained that Ideas, Concepts, Intelligible Entia, were not relative but absolute. The Eleate combats these philosophers, and establishes against them--That the Cogitable or Intelligible existence, Ens Rationis, was just as much relative to an Intelligent or Cogitant subject, as perceivable existence was relative to a Subject capable of perceiving--That Existence, under both varieties, was nothing more than a potentiality, correlating with a counter-potentiality ([Greek: to\ gnôsto\n] with [Greek: to\ gnôstiko/n], [Greek: to\ ai)sthêto\n] with [Greek: to\ ai)sthêtiko/n], and never realised except in implication therewith.[27]

[Footnote 27: Plato, Sophistes, pp. 247-248.

The view taken of this matter by Mr. John Stuart Mill, in the third chapter of the first Book of his System of Logic, is very instructive; see especially pp. 65-66 (ed. 4th).

Aristippus (one of the Sokratici viri, contemporary of Plato) and the Kyrenaic sect affirmed the doctrine--[Greek: o(/ti mo/na ta\ pa/thê katalêpta/]. Aristokles refutes them by saying that there can be no [Greek: pa/thos] without both Object and Subject--[Greek: poiou=n] and [Greek: pa/schon]. And he goes on to declare that these three are of necessary co-existence or consubstantiality. [Greek: A)lla\ mê\n a)na/gkê ge tri/a tau=ta sunuphi/stasthai--to/ te pa/thos au)to/, kai\ to\ poiou=n, kai\ to\ pa/schon] (ap. Eusebium, Præp. Ev. xiv. 19, 1).

I apprehend that Aristokles by these words does not really refute what Aristippus meant to affirm. Aristippus meant to affirm the Relative, and to decline affirming anything beyond; and in this Aristokles agrees, making the doctrine even more comprehensive by showing that Object as well as Subject are relative also; implicated both with each other and in the [Greek: pa/thos].]

[Side-note: Plato's representation of the Protagorean doctrine in intimate conjunction with the Herakleitean.]

This doctrine of the Eleate in the Platonic Sophistes coincides with the Protagorean--_Homo Mensura_--construed in its true meaning: Object is implicated with, limited or measured by, Subject: a doctrine proclaiming the relativeness of all objects perceived, conceived, known, or felt--and the omnipresent involution of the perceiving, conceiving, knowing, or feeling, Subject: the object varying with the Subject. "As things appear to me, so they are to me: as they appear to you, so they are to you." This theory is just and important, if rightly understood and explained: but whether Protagoras did so explain or understand it, we cannot say; nor does the language of Plato enable us to make out. Plato passes on from this theory to another, which he supposes Protagoras to have held without distinctly stating it: That there is no Ens distinguishable in itself or permanent, or stationary: that all existences are in perpetual flux, motion, change--acting and reacting upon each other, combining with or disjoining from each other.[28]

[Footnote 28: Plato, Theætêt. p. 152 D.

Though Plato states the grounds of this theory in his ironical way, as if it were an absurd fancy, yet it accidentally coincides with the largest views of modern physical science. Absolute rest is unknown in nature: all matter is in perpetual movement, molecular as well as in masses.]

[Side-note: Relativity of sensible facts, as described by him.]

Turning to the special theory of Protagoras (Homo Mensura), and producing arguments, serious or ironical in its defence, Sokrates says--What you call colour has no definite place or existence either within you or without you. It is the result of the passing collision between your eyes and the flux of things suited to act upon them. It is neither in the agent nor in the patient, but is something special and momentary generated in passing between the two. It will vary with the subject: it is not the same to you, to another man, to a dog or horse, or even to yourself at different times. The object measured or touched cannot be in itself either great, or white, or hot: for if it were, it would not appear different to another Subject. Nor can the Subject touching or measuring be in itself great, or white, or hot: for if so, it would always be so, and would not be differently modified when applied to a different object. _Great_, _white_, _hot_, denote no positive and permanent attribute either in Object or Subject, but a passing result or impression generated between the two, relative to both and variable with either.[29]

[Footnote 29: Plato, Theætêt. pp. 153-154. [Greek: o(\ dê\ e(/kaston ei)=nai/ phamen chrô=ma, ou)/te to\ prosba/llon ou)/te to\ prosballo/menon e)/stai, a)lla\ metaxu/ ti e(kastô| i)/dion gegono/s.]]

[Side-note: Relations are nothing in the object purely and simply without a comparing subject.]