Chapter VI: Part 6

That hypotheses, in that wide sense of the word which implies every thing conjectural, are without use in philosophy, it would be absurd to affirm, since every inquiry may, in that wide sense, be said to pre-suppose them, and must always pre-suppose them if the inquiry have any object. They are of use, however, not as superseding investigation, but as directing investigation to certain objects,--not as telling us, what we are to believe, but as pointing out to us what we are to endeavour to ascertain. An hypothesis, in this view of it, is nothing more than a reason for making one experiment or observation rather than another; and it is evident, that, without some reason of this kind, as experiment and observations are almost infinite, inquiry would be altogether profitless. To make experiments, at random, is not to _philosophize_; it becomes philosophy, only when the experiments are made with a certain view; and to make them, with any particular view, is to suppose the presence of something, the operation of which they will tend either to prove or disprove. When Torricelli, for example,--proceeding on the observation previously made, by Galileo, with respect to the limited height to which water could be made to rise in a pump,--that memorable observation, which demonstrated, at last, after so many ages of errors, what ought not for a single moment to have required to be demonstrated; the absurdity of the horror of a void ascribed to nature--when, proceeding in this memorable observation, Torricelli made his equally memorable experiment with respect to the height of the column of mercury supported in an inverted tube, and found, on comparison of their specific gravities, the columns of mercury and water to be exactly equiponderant, it is evident that he was led to the experiment with the mercury by the supposition, that the rise of fluids _in vacuo_ was occasioned by some counterpressure, exactly equal to the weight supported, and that the column of mercury, therefore should be less in height than the column of water, in the exact inverse ratio of their specific gravities, by which the counterpressure was to be sustained. To conceive the air, which was then universally regarded as essentially light, to be not light but heavy, so as to press on the fluid beneath, was, at that time, to make as bold a supposition as could be made. It was indeed, a temporary hypothesis, even when it led to that experimental demonstration of the fact, which proved it forever after not to be hypothetical.

An hypothesis, then, in the first stage of inquiry, far from being inconsistent with sound philosophy, may be said to be essential to it. But it is essential only in this first stage, as suggesting what is afterwards to be verified or disproved; and, when the experiments or observations to which it directs us do not verify it, it is no longer to be entertained, even as an hypothesis. If we observe a phenomenon, which we never have observed before, it is absolutely impossible for us, not to think of the analogous cases which we may have seen; since they are suggested by a principal of association, which is as truly a part of our constitution, as the senses with which we perceived the phenomenon itself; and, if any of these analogies strike us as remarkably coincident, it is equally impossible for us not to imagine, that the cause, which we knew in that former instance, may also be present in this analogical instance, and that they _may_, therefore, both be reduced to the same class. To stop here, and, from this mere analogy, to infer positive identity of the causes, and to follow out the possible consequences in innumerable applications, would be to do, as many great artists in systematizing have done. What a philosopher, of sounder views, however, would do in such a case, is very different. He would assume, indeed, as _possible_ or perhaps as _probable_, the existence of the supposed cause. But he would assume it, only to direct his examination of its reality, by investigating, as far as he was able, from past experience, what the circumstances would have been, in every respect, if the cause supposed had been actually present; and, even if these were all found to be exactly coincident, though he would think the presence of the cause more probable, he would be very far from considering it as certain, and would still endeavour to lessen the chances of fallacy, by watching the circumstances, should they again recur, and varying them, by experiment, in every possible way.

This patience and caution, however, essential as they are to just philosophizing, require, it must be confessed, no slight efforts of self-denial, but of a self-denial which is as necessary to intellectual excellence as the various moral species of self-denial are to excellence and virtue.

“Mr Locke, I think,” says Dr Reid, “mentions an eminent musician, who believed that God created the world in six days, and rested the seventh, because there are but seven notes in music. I myself,” he continues, “knew one of that profession, who thought that there could be only three parts in harmony, to wit, bass, tenor, and treble; because there are but three persons in the Trinity.”[30]

The minds that could be satisfied with analogies so very slight, must, indeed, have been little acquainted with the principles of philosophic inquiry; and yet how many systems have been advanced in different ages, admired by multitudes, who knew them only by name, and still more revered by the philosophers, who gloried in adopting them, that have been founded on analogies almost as slight.

“The philosophers who form hypothetical systems of the universe, and of all its most secret laws,” says Voltaire, in one of his lively similes, “are like our travellers that go to Constantinople, and think that they must tell us a great deal about the seraglio. They pretend to know every thing which passes within it--the whole secret history of the Sultan and his favourites, and they have seen nothing but its outside walls.”

In one respect, however, philosophers, in their hypothetical systems, far outdo the travellers to Constantinople. They not merely tell us secrets of nature, which they have no opportunity of learning, but they believe the very tales of their own fancy. To see any usual phenomenon, is, indeed, to wonder at it, at first; but to explain it, is almost the very next step, reason serving rather to defend the explanation, when it is made, than to assist greatly in making it; and, in many cases, each philosopher has his separate explanation, on which he is disposed to put as much reliance, as on the certainty of the fact itself, not abandoning the hypothesis, even though the fact should prove to have been different, but making it bend, with a happy pliability, to all the diversities discovered, so as at last, perhaps, to account for circumstances the very reverse of those which it was originally invented to explain. “I have heard,” says Condillac, “of a philosopher, who had the happiness of thinking that he had discovered a principle, which was to explain all the wonderful phenomena of chemistry; and who, in the ardour of his self-congratulation, hastened to communicate his discovery to a skilful chemist. The chemist had the kindness to listen to him, and then calmly told him, that there was but one unfortunate circumstance for his discovery, which was, that the chemical _facts_ were exactly the reverse of what he had supposed. Well then, said the philosopher, have the goodness to tell me _what_ they are, that I may explain them by my system.”[31] To those who know that fondness for conjecture, which may almost be said to be a sort of intellectual appetite, there is nothing in all the wonders which Swift tells us of his fabled Houynhnhms, that marks them more strongly as a different race from mankind, than the total absence of hypothesis from their systems of knowledge.

“I remember,” says Gulliver, “it was with extreme difficulty that I could bring my master to understand the meaning of the word _opinion_, or how a point could be disputable; because reason taught us to affirm or deny only when we are certain; and beyond our knowledge we cannot do either. So that controversies, wranglings, disputes, and positiveness, in false or dubious propositions, are evils unknown among the Houynhnhms. In the like manner, when I used to explain to him our several systems of Natural Philosophy, he would laugh, that a creature pretending to reason, should value itself upon the knowledge of other people's conjectures, and in things, where that knowledge, if it were certain, could be of no use. Wherein he agreed entirely with the sentiments of Socrates, as Plato delivers them, which I mention as the highest honour I can do that Prince of philosophers. I have often since reflected what destruction such a doctrine would make in the libraries of Europe, and how many paths to fame would be then shut up in the learned world.”[32]

While I wish to caution you against a fondness for hypotheses, by shewing you, not merely that they are liable to error,--for inquiry, of every kind, must be so in some degree,--but that, in truth, they leave the real difficulty of the succession of the observed consequents to the observed antecedents as great as before, and only add, to the supposed difficulty of explaining one sequence, the necessity of explaining a sequence additional,--I must remark, at the same time, that what is commonly termed _theory_, in opposition to _hypothesis_, is far from being so different from it as is commonly represented,--at least, in the very wide application which is usually made of it. We are told, by those who lay down rules of philosophizing, that the object of philosophy is, to observe particulars, and, from these, to frame general laws, which may, again, be applied to the explanation of particulars; and the view which is thus given of the real province of philosophy is undoubtedly a just one;--but there is an ambiguity in the language which may deceive you, and with respect to which, therefore, it is necessary for you to be on your guard. If, by the term _general law_, be meant the agreement in some common circumstances of a number of events observed, there can be no question that we proceed safely in framing it, and that what we have already found in a number of events, must be applicable to that number of events; in the same manner, as, after combining in the term _animal_ the circumstances in which a dog, a horse, a sheep agree, we cannot err in applying the term animal to a dog, a horse, a sheep. But the only particular to which, in this case, we can, with perfect confidence, apply a general law, are the very particulars that have been before observed by us. If it be understood as more general than the circumstances observed, and, therefore, capable of being applied with perfect certainty to the explanation of new phenomena, we evidently, to the extent in which the general law is applied beyond the circumstances observed, proceed on mere supposition, as truly, as in any hypothesis which we could have framed; and though the supposition may be more and more certain, in proportion to the number of cases thus generalized, and the absence of any circumstance which can be supposed, in the new case, to be inconsistent with it, it never can amount to actual certainty. Let us take, for example, one of the most striking cases of this sort. That bodies tend to each other, _in all circumstances_, with a force increasing directly as their quantities, and inversely as the squares of their distances, may seem in the highest degree probable indeed, from the innumerable facts observed on our globe, and in the magnificent extent of the planetary movements; but it cannot be said to be certain at all distances, in which we have never had an opportunity of making observations,--as it seems to be verified in the heights of our atmosphere, and in the distances of the planets, in their orbits, from the sun, and from each other. It is not necessary, however, to refer, for possible exceptions, to spaces that are beyond our observation; since, on the surface of our own earth, there is abundant evidence, that the law does _not_ hold _universally_. Every quiescent mass that is capable of greater compression, and of which the particles, therefore, before that compression, are not in absolute contact, shews sufficiently, that the principle of attraction, which, of itself, would have brought them into actual contact, must have ceased to operate, while there was still a space between the particles that would have allowed its free operation; and, in the phenomena of _elasticity_, and impulse in general, it has not merely ceased, but is actually reversed,--the bodies which, at all visible distances, exhibited a reciprocal _attraction_, now exhibiting a reciprocal _repulsion_, in consequence of which they mutually fly off, as readily as they before approached,--that is to say, the tendency of bodies to each other being converted into a tendency _from_ each other, by a mere change of distance, so slight as to be almost inappreciable. When a ball rebounds from the earth, toward which it moved rapidly before, and the gravitating tendency is thus evidently reversed, without the intervention of any foreign force, what eye, though it be aided by all the nicest apparatus of optical art, can discover the lines which separate those infinitesimal differences of proximity, at which the particles of the ball still continue to gravitate toward the earth, and are afterwards driven from it in an opposite direction;--yet the phenomenon itself is a sufficient proof, that in these spaces, which seem, to our organs of sense, so completely the same, that it is absolutely impossible for us to distinguish them, the reciprocal tendencies of the particles of the ball and of the earth are as truly opposite, as if the laws of gravitation had, at the moment at which the rebound begins, been reversed through the whole system of the universe.

It is, indeed, scarcely possible to imagine a more striking proof of the danger of extending, with too great certainty, a general law, than this instant conversion of _attraction_ into _repulsion_, without the addition of any new bodies, without any change in the nature of the bodies themselves, and a change of their circumstances so very slight, as to be absolutely indistinguishable, but for the opposite motions that result from it, with a change of their circumstances. After observing the gravity of bodies, at all heights of our atmosphere, and extending our survey through the wide spaces of our solar system,--computing the tendency of the planets to the sun, and their disturbing forces, as they operate on each other,--and finding the resulting motions exactly to correspond with those which we had predicted by theory;--in these circumstances, after an examination so extensive, if we had affirmed, as an universal law of matter, that, at all distances, bodies tend toward each other, we should have considered the wideness of the induction, as justifying the affirmation; and yet, even in this case, we find, on the surface of our earth, in the mutual shocks of bodies, and in their very rest, sufficient evidence, that, in making the universal affirmation, we should have reasoned falsely. There is no theory, then, which, if applied to the explanation of _new_ phenomena, is not, to a certain degree, conjectural; because it must proceed on the supposition, that what was true in certain circumstances, is true also in circumstances that have not been observed. It admits of certainty, only when it is applied to the very substances observed,--in the very circumstances observed,--in which case, it may be strictly said to be nothing more than the application of a general term to the particulars, which we have before agreed to comprehend in it. Whatever is more than this is truly hypothetical,--the difference being, that we commonly give the name of _hypothesis_ to cases, in which we suppose the intervention of some substance, of the existence of which, as present in the phenomenon, we have no direct proof, or of some additional quality of a substance before unobserved,--and the name of _theory_ to cases, which do not suppose the existence of any substance, that is not actually observed, or of any quality that has not been actually observed, but merely the continuance, in certain _new_ circumstances, of tendencies observed in other circumstances. Thus, if a planet were discovered revolving in the space which separates the orbits of any two planets at present known, were we to suppose of matter, in this new situation, that it would be subject to the same exact law of gravitation, to which the other planets were known to be subject, and to predict its place in the heavens, at any time, according to this law, we should be said to form a theory of its motions; as we should not take for granted, any new quality of a substance, or the existence of any substance, which was not evidently present, but only of _tendencies_ observed before in other circumstances,--analogous indeed, but not absolutely the same. We should be said to form an hypothesis on the subject, if, making the same prediction, as to its motions, and place in the heavens, at any given time, we were to ascribe the centripetal tendency, which confines it within its orbit, to the impulse of ether, or to any other mechanical cause. The terms, however, I must confess, though the distinction which I have now stated would be, in all cases, a very convenient one, are used very loosely, not in conversation merely, but in the writings of philosophers,--an hypothesis often meaning nothing more than a theory, to which we have not given our assent,--and a theory, an hypothesis which we have adopted, or still more, one which we have formed ourselves.

A _theory_, then, even in that best sense, to which I wish it accurately confined, as often as it ventures a single hair-breadth beyond the line of former observation, may be wrong, as an hypothesis may be wrong. But, in a theory, in this sense of it, there are both less risk of error, and less extensive evil from error, than in an hypothesis. There is less risk of error, because we speak only of the properties of bodies, that must be allowed actually to exist; and the evil of error is, for the same reason, less extensive, since it must be confined to this single point; whereas, if we were to imagine falsely the presence of some third substance, our supposition might involve as many errors, as that substance has qualities; since we should be led to suppose, and expect, some or all of the other consequences, which usually attend it, when really present.

The practical conclusion to be drawn from all this very long discussion, is, that we should use hypotheses to suggest and direct inquiry, not to terminate or supersede it; and that, in theorizing,--as the chance of error, in the application of a general law, diminishes, in proportion to the number of analogous cases, in which it is observed to hold,--we should not form any general proposition, till after as wide an induction, as it is possible for us to make; and, in the subsequent application of it to particulars, should never content ourselves, in any new circumstances, with the mere probability, however high, which this application of it affords; while it is possible for us to verify, or disprove it, by actual experiment.

FOOTNOTES:

[30] On the Powers of the Human Mind, Essay vi. Chap. viii. Vol. II. p. 334. 8vo. _edit._

[31] Traite des Systemes, chap. xii. Vol. II. p. 372.

[32] Travels, Part iv, chap. 8. Swift's Works, _edit._ Nichols, Vol. ix. p. 300.

LECTURE IX.

RECAPITULATION OF THE FOUR PRECEDING LECTURES; AND APPLICATION OF THE LAWS OF PHYSICAL INQUIRY TO THE STUDY OF MIND, COMMENCED.

For several Lectures, Gentlemen, we have been employed in considering the objects that are to be had in view, in Physical Inquiry in general, a clear conception of which seems to me as essential to the Philosophy of Mind, as to the Philosophy of Matter. I should now proceed to apply these general remarks more particularly to our own science; but, before doing this, it may be of advantage to retrace slightly our steps in the progress already made.

All inquiry, with respect to the various substances in nature, we have seen, must regard them as they exist in _space_, or as they exist in _time_,--the inquiry, in the one case, being into their composition; the inquiry, in the other case, into the changes which they exhibit. The first of these views we found to be very simple, having, for its object, only the discovery of what is actually before us at the moment,--which, therefore, if we had been endowed with senses of greater delicacy and acuteness, we might have known, without any inquiry whatever. It is the investigation of the elements, or separate bodies, that exist together, in the substances which we considered, or rather that constitute the substances which we considered, by occupying the space which we assign to the one imaginary aggregate, and are regarded by us as one substance,--not from any absolute unity which they have in nature, since the elementary atoms, however continuous or near, have an existence as truly separate and independent, as if they had been created at the distance of worlds,--but from a unity, that is relative only to our incapacity of distinguishing them as separate. It is to the imperfection of our senses, then, that this first division of Physical Inquiry owes its origin; and its most complete results could enable us to discover only, what has been before our eyes from the moment of our birth.

The second division of inquiry,--that which relates to the successions of phenomena in time,--we found, however, to have a different origin; since the utmost perfection of our mere senses could show us only what _is_, at the moment of perception, not what _has been_, nor what _will be_; and there is nothing in any qualities of bodies perceived by us, which, without experience, could enable us to predict the changes that are to occur in them. The foundation of all inquiry, with respect to phenomena as successive, we found to be that most important law, or original tendency, of our nature, in consequence of which we not merely perceive the changes exhibited to us at one particular moment, but from this perception, are led irresistibly to believe, that similar changes _have_ constantly taken place, in all similar circumstances, and _will_ constantly take place, as often as the future circumstances shall be exactly similar to the present. We hence consider events, not as casually antecedent and consequent, but as invariably antecedent and consequent,--or, in other words, as causes and effects; and we give the name of _power_ to this permanent relation of the invariable antecedent to its invariable consequent. The powers of substances, then, concerning which so many vague, and confused, and mysterious notions prevail, are only another name for the substances themselves, in relation to other substances,--not any thing separate from them and intermediate,--as the _form_ of a body, concerning which too, for many ages, notions as vague and mysterious prevailed, is not any thing different from the body, but is only the body itself, considered according to the relative position of its elements. Form is the relation of immediate proximity, which bodies bear to each other in _space_;--power is the relation of immediate and uniform proximity, which events bear to each other in _time_; and the relation, far from being different, as is commonly supposed, when applied to matter and to spirit, is precisely the same in kind, whether the events, of which we think, be material or immaterial. It is of invariable antecedence that we speak alike in both cases, and of invariable antecedence only. When we say, that a magnet has the power of attracting iron, we mean only, that a magnet cannot be brought near iron, without the instant motion of the iron towards it. When we say, in treating of _mental_ influence, that man, in the ordinary circumstances of health, and when free from any foreign restraint, has the power of moving his hand, we mean only, that, in these circumstances, he cannot will to move his hand, without its consequent motion. When we speak of the omnipotence of the Supreme of Beings,--who is the fountain of all power, as he is the fountain of all existence,--we mean only, that the universe arose at his command, as its instant consequence, and that whatever he _wills_ to exist or perish, exists, or is no more.

This simple view of power, as the mere antecedent substance itself, in its relation to its immediate and invariable consequences, without the intervention of any mysterious tie,--since there surely can be nothing in nature, but all the substances which exist in nature,--it was necessary to illustrate, at great length, in consequence of the very false notions, that are generally, or, I may say, universally prevalent on the subject. The illustration, I am aware, must, to many of you, have appeared very tedious, and a sufficient exemplification of that license of exhausting occasionally your attention, and perhaps, too, your patience, of which I claimed the right of exercise, whenever it should appear to me necessary, to make any important, but abstract truth familiar to your mind. I shall not regret, however, any temporary feeling of weariness which I may have occasioned, by dwelling on this great fundamental subject, if I have succeeded in making familiar to your minds, the truths which I wished to impress on them, and have freed you from those false notions of occult and unintelligible agency in causes,--as something different from the mere causes or antecedents themselves,--which appear to me to have retarded, in a very singular degree, the progress of philosophy,--not merely, by habituating the mind to acquiesce in the use of language, to which it truly affixes no meaning, though even this evil is one of very serious injury in its general effects,--but by misdirecting its inquiries, and leading it, from the simplicity of nature,--in which every glance is truth, and every step is progress,--to bewilder itself, with the verbal mysteries of the schools, where there is no refreshment of truth to the eye, that is wearied with wandering only from shadow to shadow,--and where there is all the fatigue of continual progress, without the advance of a single step.

Even those philosophers, who have had the wisdom to perceive, that man can never discover any thing in the phenomena of nature, but a succession of events, that follow each other in regular series,--and who, accordingly, recommend the observation and arrangement of these regular antecedents and consequents, as the only attainable objects of philosophy, yet found this very advice, on the distinction of what they have termed efficient causes, as different from the physical causes, or simple antecedents, to which they advise us to devote our whole attention. There are certain _secret causes_, they say, continually operating in the production of every change which we observe, and causes which alone deserve the name of efficient; but they are, at the same time, careful to tell us, that, although these causes are constantly operating before us, and are all which are truly acting before us, we must not hope, that we shall ever be able to detect one of them; and indeed, the prohibition of every attempt to discover the efficient causes of phenomena,--repeated in endless varieties of precept or reproof,--is the foundation of all their rules of philosophizing; as if the very information,--that what we are to consider exclusively, in the phenomena of nature, is far less important, than what we are studiously to omit,--were not, of itself, more powerful, in stimulating our curiosity to attempt the forbidden search, than any prohibition could be in repressing it. “Felix qui potuit rerum cognoscere causas.” This will forever be the feeling of the inquirer, while he thinks that there are any causes, more than those, which he has already investigated. Even Newton himself, that sagest of observers and reasoners, who could say, with the simplicity of pure philosophy, “_Hypotheses non fingo._” yet showed, as we have seen, by one of the most hypothetical of his Queries, that he was not exempt from the error which he wished to discourage--that inordinate love of the unknown, which must always lead those, who believe that there is something intermediate and undiscovered truly existing between events, to feel the anxious dissatisfaction of incomplete inquiry, in considering the mere antecedents and consequents which nature exhibits, and to turn, therefore, as if for comfort, to any third circumstance, which can be introduced, without obvious absurdity, as a sort of connecting link, between the pairs of events. To suppose that the mind should not have this disposition, would, indeed, be to suppose it void of that principle of curiosity, without which there can be no inquiry of any kind. He who could believe, that, between all the visible phenomena, there are certain invisible agencies continually operating, which have as real an existence as all that he perceives, and could yet content himself with numbering the visible phenomena, and giving them names, without any endeavour to discover the intervening powers, by which he is constantly surrounded, or at least to form some slight _guess_, as to that universal machinery, by which he conceived all the wonders of nature to be wrought, must be a being as different from the common intellectual beings of this earth, as the perfect sage of the Stoics from the frail creatures, of mingled vice and virtue, that live and err around us. That, in considering the phenomena of nature, we should confine our attention to the mere antecedents and consequents, which succeed each other in regular series, is unquestionably the soundest advice that can be given. But it is sound advice, for this reason more than any other, that the regular series is, in truth, all that constitutes the phenomena, and that to search for any thing more, is not to have an unattainable object in view, but to have no conceivable object whatever. _Then only_ can the inquirer be expected to content himself with observing and classing the sequences, which nature presents to us spontaneously, or in obedience to our art, when he is convinced, that all the substances which exist in the universe--God and the things which he has created--are every thing which truly exists in the universe, to which nothing can be added, which is not itself a _new_ substance; that there can be nothing in the events of nature, therefore, but the antecedents and consequents which are present in them; and that these, accordingly, or nothing, are the very causes and effects, which he is desirous of investigating.

After this examination of the notions connected with the uniform successions of events, our attention was next turned to the nature and origin of _hypothetical inquiry_, which we found reason to ascribe to the imperfection of our senses, that renders it impossible for us to know whether we have observed the whole train of sequences in any phenomenon, from our inability to distinguish the various elements that may be the subjects of minute changes unobserved.

We are hence eager to supply, by a little guess-work of fancy, the parts unobserved, and suppose deficiencies in our observation where there may truly have been none; till at length, by this habitual process, every phenomenon becomes, to our imagination, the sign of something _intermediate_ as its cause, the discovery of which is to be an explanation of the phenomenon. The mere succession of one event to another appears, to us, very difficult to be conceived, because it wants that intervening something, which we have learned to consider as a cause; but there seems to be no longer any _mystery_, if we can only suppose something intervening between them, and can thus succeed in doubling the difficulty, which we flatter ourselves with having removed; since, by the insertion of another link, we must now have two sequences of events instead of one simple sequence. This tendency of the imagination to form and rest on hypotheses,--or, in other words, to suppose substances present and operating, of the existence of which we have no direct proof,--we found to be one great source of error in our practice of philosophizing.

Another source of error, we found to be the _too great extension_ of what are termed general laws; which though a less error in itself, is yet, in one respect, more dangerous than the former; because it is the error of better understandings,--of understandings that would not readily fall into the extravagant follies of hypotheses, but acknowledge the essential importance of induction, and think they are proceeding on it without the slightest deviation, almost at the very moment when they are abandoning it for conjecture. To observe the regular series of antecedents and consequents, and to class these as similar or dissimilar, are all which philosophers can do with complete certainty. But there is a constant tendency in the mind, to convert a _general_ law into an _universal_ law,--to suppose, after a wide induction, that what is true of many substances that have a very striking analogy, is as certainly true of _all_ that have this striking analogy,--and that what is true of them in _certain_ circumstances, is true of them in _all_ circumstances,--or, at least, in all circumstances which are not remarkably different. The widest induction which we can make, however, is still limited in its nature; and, though we may have observed substances in many situations, there may be some new situations, in which the event may be different, or even, perhaps, the very reverse of that which we should have predicted, by reasoning from the mere analogy of other circumstances. It appeared to me necessary, therefore, in consequence of the very ambiguous manner in which writers on this higher branch of logic speak of reasoning from general laws to particulars, to warn you, that the application to particulars can be made with certainty, only to the very particulars before observed and generalized,--and that, however analogous other particulars may seem, the application of the general law to them admits only of _probability_, which may, indeed, as the induction has been wider, and the circumstances of observed analogy more numerous, approach more or less to certainty, but must always be short of it, even in its nearest approximation.

* * * * *

Such, then, is _physical inquiry_, both as to its objects, and its mode of procedure, particularly as it regards the universe without; and the laws which regulate our inquiry in the internal world of thought are, in every respect, similar. The same great objects are to be had in view, and no other,--the analysis of what is complex, and the observation and arrangement of the sequences of phenomena, as respectively antecedent and consequent.

In this respect, also, I may remark, the philosophy of matter and the philosophy of mind completely agree--that, in both equally, our knowledge is confined to the phenomena which they exhibit. We give the name of _matter_ to the unknown cause of various feelings, which, by the constitution of our nature, it is impossible for us not to refer to something external as their cause. What it is, independent of our perception, we know not; but as the subject of our perception, we regard it as that which is extended, and consequently divisible, impenetrable, mobile; and these qualities, or whatever other qualities we may think necessary to include for expressing the particular substances that affect our senses variously, constitute our whole definition of matter, because, in truth, they constitute our whole knowledge of it. To suppose us to know what it is in itself, in absolute independence of our perception, would be manifestly absurd: since it is only by our perception,--that is to say, by the feelings of our mind,--that it can be known to us at all; and these mere feelings of the mind must depend, at least, as much on the laws of the mind affected, as on the laws of the substance that affects it. Whatever knowledge we may acquire of it, therefore, is relative only, and must be relative in all circumstances; though, instead of the few senses which connect us with it at present, we were endowed with as many senses as there are, perhaps, qualities of matter, the nature of which we are at present incapable of distinguishing;--the only effect of such increased number of senses being, to render more qualities of matter known to us, not to make matter known to us in its very essence, as it exists without relation to mind.

“Tell me,” says Micromegas, an inhabitant of one of the planets of the Dog Star, to the secretary of the Academy of Sciences in the planet Saturn, at which he had recently arrived in a journey through the heavens,--“Tell me, how many senses have the men on your globe?”--I quote, as perhaps the name has already informed you from an ingenious philosophic romance of Voltaire, who, from various allusions in the work, has evidently had Fontenelle, the illustrious secretary of the French Academy of Sciences, in view, in the picture which he gives of the Saturnian secretary.--“We have seventy-two senses,” answered the academician, “and we are, every day, complaining of the smallness of the number. Our imagination goes far beyond our wants. What are seventy-two senses! and how pitiful a boundary, even for beings with such limited perceptions, to be cooped up within our ring, and our five moons! In spite of our curiosity, and in spite of as many passions as can result from six dozen of senses, we find our hours hang very heavily on our hands, and can always find time enough for yawning.”--“I can very well believe it,” says Micromegas, “for, in our globe, we have very near _one thousand_ senses; and yet, with all these, we feel continually a sort of listless inquietude and vague desire, which are forever telling us that we are nothing, and that there are beings infinitely nearer perfection. I have travelled a good deal in the universe. I have seen many classes of mortals far beneath us, and many as much superior; but I have never had the good fortune to find any, who had not always more desires than real necessities to occupy their life.--And, pray, how long may you Saturnians live with your few senses?” continued the Sirian.--“Ah! but a very short time, indeed!” said the little man of Saturn, with a sigh.--“It is the same with us,” said the traveller; “we are forever complaining of the shortness of life. It must be an universal law of nature.”--“Alas!” said the Saturnian, “we live only five hundred great revolutions of the sun (which is pretty much about fifteen thousand years of our counting.) You see well, that this is to die almost the moment one is born. Our existence is a point--our duration an instant--our globe an atom. Scarcely have we begun to pick up a little knowledge, when death rushes in upon us, before we can have acquired any thing like experience. As for me, I cannot venture even to think of any project. I feel myself but like a drop of water in the ocean; and, especially now, when I look to you and to myself, I really feel quite ashamed of the ridiculous appearance which I make in the universe.”

“If I did not know that you were a philosopher,” replied Micromegas, “I should be afraid of distressing you, when I tell you, that our life is seven hundred times longer than yours.--But what is even that? and, when we come to the last moment, to have lived a _single day_, and to have lived a _whole eternity_, amount to the very same thing. I have been in countries where they live a thousand times longer than with us; and I have always found them murmuring, just as we do ourselves.--But you have seventy-two senses, and they must have told you something about your globe. How many properties has matter with you?”--“If you mean _essential_ properties,” said the Saturnian, “without which our globe could not subsist, we count three hundred, extensive, impenetrable, mobile, gravitation, divisibility, and so forth.”--“That small number,” replied the gigantic traveller, “may be sufficient for the views which the Creator must have had with respect to your narrow habitation. Your globe is little; its inhabitants are so too. You have few senses; your matter has few qualities. In all this, Providence has suited you most happily to each other.”

“The academician was more and more astonished with every thing which the traveller told him. At length, after communicating to each other a little of what they knew, and a great deal of what they knew _not_, and reasoning, as well and as ill, as philosophers usually do, they resolved to set out together, on a little tour of the universe.”[33]

That, with the one thousand senses of the Sirian, or even the seventy-two senses of the inhabitant of Saturn, our notions of matter would be very different from what they are at present, cannot be doubted; since we should assign to it qualities, corresponding with all the varieties of our six dozen or one thousand classes of sensations. But, even with all these sensations, it is evident, that we should still know as little of _matter_, independent of the phenomena which it exhibits in relation to us, as we know, at this moment. Our definition of it would comprehend more phenomena; but it would still be a definition of its phenomena only. We might perhaps be able to fill up the Saturnian catalogue of three hundred essential properties, but these would be still only the relations of matter to our own perception. A change in the mere susceptibility of our organs of sense, or of our sentient mind, would be relatively to us, like a change in the whole system of things, communicating, as it were, new properties to every object around us. A single sense additional, in man, might thus be to external nature, like the creation of the sun, when he first burst upon it in splendour, “like the god of the new world,” and pouring every where his own effulgency, seemed to shed on it the very beauties which he only revealed.

If our knowledge of matter be relative only, our knowledge of mind is equally so. We know it only as susceptible of feelings that have already existed, and its susceptibilities of feelings which have not arisen, but which may, in other circumstances, arise, we know as little, as the blind can be supposed to know of colours, or as we, with all our senses, know of the qualities which matter might exhibit to us, if our own organization were different. Of the _essence_ of mind, then, we know nothing, but in relation to the states or feelings that form, or have formed, our momentary consciousness. Our knowledge is not absolute but relative; though, I must confess, that the term _relative_ is applied, in an unusual manner, when, as in the present instance, the relative and correlative are the same. It is unquestionably the same individual mind, which, in intellectual investigation, is at once the object and the observer. But the noble endowment of memory, with which our Creator has blessed us, solves all the mystery of this singular paradox. In consequence of this one faculty, our mind, simple and indivisible as it truly is, is, as it were multiplied and extended, expanding itself over that long series of sensations and emotions, in which it seems to live again, and to live with many lives. But for memory, there can be no question that the relation of thought to thought could not have been perceived; and that hence there could have been no philosophy whatever, intellectual or moral, physical or metaphysical. To this wonderful endowment, then, which gives us the past to compare with the present, we owe that most wonderful of relations, of which the same being is at once the _object_ and the _subject_, contemplating itself, in the same manner, as it casts its view on objects that are distant from it, comparing thought with thought, emotion with emotion, approving its own moral actions, with the complacency with which it looks on the virtues of those whom it admires and loves, in the most remote nation or age, or passing sentence on itself, as if on a wretch whom it loathed, that was trembling with conscious delinquency, under the inquisition of a severe and all-knowing judge.

The past feelings of the mind, then, are, as it were, objects present to the mind itself, and acquire, thus truly, a sort of relative existence, which enables us to class the phenomena of our own spiritual being as we class the phenomena of the world without. The mind is that which we know to have been susceptible of all the variety of feelings which we remember; and it is only as it is susceptible of all these varieties of feeling, that we can have any knowledge of it. We define it therefore, by stating its various susceptibilities, including more or fewer of these, in our definition, as we may either have observed or remembered more or less, or generalized more or less what we have observed and remembered; precisely as in our definition of matter, we include more or fewer qualities, according to the extent of our previous observation and arrangement.

That we know _matter_, only as relative to our own susceptibility of being affected by it, does not lessen the value of the knowledge of it, which we are able to acquire; and, indeed, it is only as it is capable of affecting us, that the knowledge of it can be of any direct and immediate utility. It would, indeed, be the very absurdity of contradiction, to suppose ourselves acquainted with qualities which cannot affect us. But, even though this were possible, how profitless would the knowledge be, compared with the knowledge of the qualities which are capable of affecting us; like the knowledge of the seasons of the planet Saturn, or of the planets that have the Dog Star for their sun, compared with the more important knowledge of the seasons of our own globe, by which we have the comfort of anticipating, in the labours of spring, the abundance of autumn, and gather in autumn the fruits, which, as products of vernal labour, are truly fruits of the spring.

To know _matter_, even _relatively_, as our limited senses allow us to know it, is to have knowledge which can scarcely be called limited. Nothing, indeed, can seem more narrow in extent, if we think only of the small number of our senses, by which alone the communication can be carried on. But what infinity of objects has nature presented to each! In the mere forms and colours that strike our eyes, what splendid variety! the proportion of all things that bloom or live, the earth, the ocean, the universe, and almost God himself appearing to our very senses, in the excellence and beauty of the works which He has made!

It is the same, with respect to the _mind_, though we know it only by its susceptibilities of affection, in the various feelings of our momentary consciousness, and cannot hope to know it, but as the permanent subject of all these separate consciousnesses; to know thus relatively only, the affections even of one single substance, is to have a field of the most boundless and inexhaustible wonders ever present and open to our inquiry! It may be said to comprehend every thing which we perceive, and remember, and imagine, and compare, and admire, all those mysterious processes of thought, which, in the happy efforts of the philosopher and the poet, are concerned in the production of their noblest results, and which are not less deserving of our regard, as they are every moment exercised by all, in the humble intellectual functions of common life. In analyzing and arranging the mental phenomena, then, we consider phenomena, that are diversified, indeed, in individuals, but, as species, are still common to all; for there is no power possessed by the most comprehensive intellect, which it does not share, in some proportion, with the dullest and rudest of mankind. All men perceive, remember, reason,--all, to a certain degree at least, from their little theories, both physical and metaphysical, of the conduct of their fellow men, and of the passing events of nature; and all, occasionally, enliven their social intercourse, or their solitary hours, with inventions of fancy, that last but for a moment indeed, and are not worthy of lasting longer, but which are products of the same species of intellectual energy, that gave existence to those glorious works, to which ages have listened with increasing reverence, and which, immortal as the spirits that produced them, are yet to command the veneration of every future age. When we see before us, in its finished magnificence, a temple, appropriated to the worship of the Supreme Being, and almost worthy of being filled with his presence, we scarcely think that it is erected according to the same simple principles, and formed of the same stone and mortar, as the plain dwellings around us, adapted to the hourly and humble uses of domestic life; and by a similar illusion, when we consider the splendid works of intellectual art, we can scarcely bring ourselves to think, that genius is but a form of general tendencies of association, of which all partake; and that its magnificent conceptions, therefore, rise, according to the same simple laws which regulate the course of thought of the vulgar. In this universality of diffusion as general tendencies, that may be variously excited by varying circumstances, our intellectual powers are similar to those other principles of our nature,--our emotions, and whatever feelings more immediately connected with moral action have been usually distinguished by the name of our active powers. In the philosophy of both we consider, not a few distinguished individuals, as possessed of principles essentially distinct in kind, but the species _man_. They are to be found, wherever there is a human being; and we do not infer with more certainty, when we perceive the impression of a foot upon the sand, that man has been there, than we expect to find in him, whatever may be his state of barbarism or civilization, some form of the common powers, and passions, which, though directed perhaps to different objects, we have felt and witnessed in the society around us. “The two-legged animal,” says Dr Reid, “that eats of nature's dainties what his taste or appetite craves, and satisfies his thirst at the crystal fountain; who propagates his kind as occasion and lust prompt; repels injuries, and takes alternate labour and repose; is like a tree in the forest, purely of nature's growth. But this same savage has within him the seeds of the logician, the man of taste and breeding, the orator, the statesman, the man of virtue, and the saint; which seeds, though planted in his mind by nature, yet, through want of culture and exercise, must lie forever buried, and be hardly perceivable, by himself, or by others.”[34] Even of those passions of a prouder kind, which attract our attention only when they are on a theatre that allows their full display, some vestiges are to be traced universally; though in different individuals, they may exist with very different degrees of influence, and though their influence, according to the degree of power possessed by the individual, may be attended with very different consequences, to the few, or the many, comprehended within the wide or narrow circle, to which his power extends.

----“Not kings alone,
Each villager has his ambition to;
No sultan prouder than his fetter'd slave.
Slaves build their little Babylons of straw,
Echo the proud Assyrian in their hearts,
And cry, Behold the wonders of my might.”[35]

It is this universal diffusion of sympathies and emotions, indeed, which gives its whole force to morality, as a universal obligation; and renders _ethics_ truly a _science_.

Nature, in requiring the fruits of virtue from all, has not fixed the seeds of it, only in a few breasts. “Nulli præclusa virtus est, omnibus patet, omnes admittit, omnes invitat, ingenuos, libertinos, servos, reges et exsules; non eligit domum, nec censum; nudo homine contenta est.”[36] Virtue has no partial favours or exclusions. She is open to all, she admits all, she invites all. She asks no wealth nor ancestry; but she asks the man,--the master or the slave, the cottager and his lord, the sovereign and the exile.