Chapter X (10)

Probably George Glen, who was installed Prebend of Worcester in 1660,
and died in 1669.

Footnote 4:

The History of the Sabbath. In two books. By Peter Heylyn. 4to. 1636.

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IV.
LETTER TO SIR CHARLES CAVENDISH.[5]

HONORABLE SIR,

The last weeke I had the honor to receave two letters from you at once, one of the 30 of Dec., the other of the 7^{th} of Jan., w^{ch} I acknowledged, but could not answer in my last. In the first you begin with a difficulty on the principle of Mons^r de Cartes, _that it is all one to move a weight two spaces, or the double of that waight one space_, and so on in other proportions: to w^{ch} you object the difference of swiftnesse, w^{ch} is greater when a waight is moved two spaces than when double waight is moved one space. Certenly de Cartes his meaning was by force the same that mine, namely, a multiplication of the weight of a body in to the swiftnesse wherew^{th} it is moved. So that when I move a pound two foote at the rate of a mile an howre, I do the same as if of 2 poundes I moved one pound a foote at y^e rate of a mile an howre, the other pound another foote at the same rate, not in directū, but parallell to the first pound. As if the wayt A B were moved to C D at the rate of a mile an howre, ’tis all one as if the waight A E were moved to F H at the same rate. Here is all the difference: this swiftnesse or rate of a mile an howre is, in the first case, layd out in the 2 spaces A G, G C, the latter, in the 2 spaces A G, E G. The first case, as like as if a footman should run w^{th} double swiftnesse endwayes, w^{ch} is y^e doubling of swiftnesse in one man: in the other, it is as if you doubled the swiftnesse by doubling the man: for every man has his owne swiftnesse. And so A H is the swiftnesse A G doubled, as well as A D. For that, that Mons^r de Cartes will not have just twice the force requisite to move the same weight twice as fast, I can say nothing. The papers I have of his touching that are in my trunk, w^{ch} hath bene taken by Dunkerkers, and taken againe from them by French, and at length recovered by frends I made: but I shall not have it yet this fortnight. In the meane time I am not in that opinion, but do assure myself, the patient being the same, double force in the agent shall worke upon it double effect.

In the same letter you require a better explication of y^e proportion I gather betweene wayght and swiftnesse: wherein, because you have not my figure, I imagine you have mistaken me very much. And first, you thinke, I suppose, D E equall to A B: w^{ch} I am sure is a mistake. For I put A B for any line you will to expresse a _minutū secundum_. I will, therefore, go over againe the demonstration I sent you before, and see if I can do it cleerer.

Let A B stand for the time knowne wherein the waight D descendeth to E. And let there bee a cylinder of the same matter the waight D consisteth of, and let the altitude of that cylinder be D C: w^{ch} I shew before was the swiftnesse wherew^{th} that cylinder _presseth_, not wherew^{th} it _falleth_. And wee are now to enquire how farre such matter as the cylinder is made of must descend from D, before it attayne a swiftnesse equall to this pressing swiftnesse D C. And I say it must fall to L. For in the time A B it is knowne that the waight in D will fall to E: and it is demonstrated by Gallileo, that when such waight comes to E, it shall be able to go twice the space it hath fallen in the same time. Therefore the waight D being in E, hath velocity to carry him the space D K (w^{ch} I put double to D E) in the same time A B. But I put B F equall to D K. Therefore, in the time A B, the waight’s velocity acquired in E shall be such as to go from B to F without decrease of velocity by the way. Hence I go on to finde in what point the waight in D comes to where it getteth a velocity equall to C D. Therefore, I apply D C to G H, parallel to B F: and then it is, as the time A B to the time A G, so the velocity acquired at the end of the time A B to the velocity acquired at the end of the time A G. For the swiftnesse acquired from time to time (I say, not from place to place, but from time to time) are proportionable to the times wherein they are acquired: w^{ch} is the postulate on w^{ch} Galileo builds all his doctrine. And as A B to A G, so the line B F to the line G H. But, at the end of the time A B, the waight D is by supposition in E, in that degree of velocity as to go B F or D K in the same time A B. The question therefore is, where the waight D shall be at the end of the time A G. For there it hath the velocity of going G H or D C in the same time, because the velocity G H is to the velocity B F as the line G H to the line B F, or as the time of descent A G to the time A B. But, because the spaces of the descent are in double the proportion of the times of descent, make it as B F to G H, that is, D K to D C, so D C to another, D L. The velocity, therefore, acquired in the point of descent E, namely the velocity D K or B F, is to the velocity acquired in the point L, namely, the velocity G H or D C, (w^{ch} is the velocity of the cylinder’s waight), as D K to D L. And therefore in L the waight D has acquired a velocity equal to the velocity of the waight of the cylinder.

In the same letter you desire to knowe, how any mediū, as water, retardeth the motion of a stone that falls into it. To w^{ch} I answer out of that you say afterwards, that nothing can hinder motion but contrary motion: that the motion of the water, when a stone falls into it, is point blanke contrary to the motion of the stone. For the stone by descent causeth so much water to ascend as the bignesse of the stone comes to. For imagine so much water taken out of the place w^{ch} the stone occupies, and layd upon the superficies of the water: it presseth downeward as the stone does, and maketh the water that is below to rise upwards, and this rising upwards is contrary to the descent, and is no other operation than we see in scales, when of two equal bullets in magnitude that w^{ch} is of heavier metal maketh the other to rise. And thus farre goes your letter of Dec. 30.

For the first quære in your second letter, concerning how we see in the time the lucide body contracts itselfe, I have no other solution but that w^{ch} your selfe hath given: w^{ch} is, that the reciprocation is so quicke, that the effect of the first motion lasteth till the next comes, and longer. For by experience we observe that the end of a firebrand swiftely moved about in circle, maketh a circle of fire: w^{ch} could not be, if the impression made at the beginning of the circulation did not last till the end of it. For if the same firebrand be moved slower, there will appear but a peece of a circle, bigger or lesser according to the swiftnesse or slownesse of y^e motion. For the cause of such reciprocation, it is hard to guess what it is. It may well be the reaction of the medium. For though the mediū yeld, yet it resisteth to: for there can be no passion w^{th}out reaction. And if a man could make an hypothesis to salve that contraction of y^e sun, yet such is the nature of naturall thinges, as a cause may be againe demanded of such hypothesis: and never should one come to an end w^{th}out assigning the immediate hand of God. Whereas in mathematicall sciences wee come at last to a definition, w^{ch} is a beginning or principle, made true by pact and consent amongst ourselves. Further, you conceave a difficulty how the medium can be continually driven on, if there be such an alternate contraction. To w^{ch}, first I answer, that the motion forward is propagated to the utmost distance in an instant, and the first push is therefore enough, and in another instant is made the returne back in y^e like manner. And though it were not done in an instant, yet we see by experience in rivers, as in y^e Thames, that the tide goes upward towards London pushed by the water below, and yet at the same instant the water below is going backe to the sea. For seeing it is high-water at Blackwall before ’tis so at Greenwich, the water goes backe from Blackwall when it goes on at Greenwich. And so it would happen, though Blackwall and Greenwich were nerer together then that any quantity given could come betweene.

In my letter from London, speaking of the refraction of a bullet, I thinke I delivered my opinion to be, that a bullet falling out of a thinner medium into a thicker, looseth in the entring nothing but motion perpendicular: but being entred, he looseth proportionably both of one and the other. For suppose a bullet, whose diameter is A B, be in the thiner mediū, and enter at C into the thicker medium. The thicker medium, at the first touch of B in the point C, worketh nothing upon the line A B. And when the diameter A B is entred, suppose halfe way, yet the thicker medium operates laterally but on one halfe of it. So that in the somme there is a losse of velocity perpendicular (to the quantity that the diameter A B requires) without any offence to the motion laterall, but so much of the diameter as is within the thicker mediū is retarded both wayes, and looses of his absolute motion, w^{ch} is compounded of perpendicular and laterall, and that proportionally. Suppose now that a bullet passe from A to D, and receave a peculiar losse of his perpendicular motion by entring at D, so great that he proceed in the perpendicular but halfe so farre, as for example from D to I: and then being in, the thicknesse of the medium take away more of his velocity both perpendicular and laterall, suppose halfe that w^{ch} was left of the perpendicular motion and halfe of his first laterall motion, so that the perpendicular motion is but D K, and the laterall motion D E. Then will the line of refraction be D G. As for that argumentation of Des Cartes, it is, in my opinion, as I have heretofore endeavored to shew you, a mere paralogism.

Lastly, you make this quære, why light hath not at severall inclinations severall swiftnesses as well as a bullet. The bullet itself passeth through the severall media: whereas in the motion of light, the body moved, w^{ch} is the mediū, entreth not into the other medium, but thrusteth it on: and so the parts of that medium thrust on one another, whereby the laterall motion of the thicker medium hath nothing to worke upon, because nothing enters, but stoppes onely and retardes, in oblique _incidence_, that end w^{ch} comes first to it, and thereby causes a refraction the contrary way to that of a bullet, in such manner as I set forth to you in one of my letters from hence concerning the cause of refraction. And this is all I can say for the present to the quæres of y^r two last letters.

I have enquired concerning perspectives after the manner of De Cartes. Mydorgius tells me there is none that goes about them, as a thing too hard to do. And I believe it. For here is one Mons^r de Bosne in towne, that dwells at Bloys, an excellent workman, but by profession a lawier, and is counsellor of Bloys, and a better philosopher in my opinion then De Cartes, and not inferior to him in the analytiques. I have his acquaintance by Pere Mersenne. He tells me he hath tryed De Cartes his way, but cannot do it: and now he workes upon a crooked line of his owne invention. He sayes he shall have made one w^{th}in a moneth after he shall returne to Bloys: after that he will see what he can discover in the heavens himselfe, and then if he discover any new thing he will let his way be publique together w^{th} the effects. This is all the hope I can give you yet. So w^{th} my prayers to God to keepe you in prosperity this troublesome time, I rest

Your most humble and obedient servant
TH. HOBBES.

_Paris, Feb. 8, stile no. 1641._

To the Right Honorable
Sr CHARLES CAVENDYSSHE
present these

/
/
/
/
at Wellinger.

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Footnote 5:

Harleian MS. 6796.

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V.
LETTER TO MR. BEALE.[6]

SIR,

The young woman at Over-Haddon hath been visited by divers persons of this house. My Lord himself hunting the hare one day at the Town’s end, with other gentlemen and some of his servants, went to see her on purpose: and they all agree with the relation you say was made to yourself. They further say on their own knowledge, that part of her Belly touches her Back-bone. She began (as her Mother says) to loose her appetite in December last, and had lost it quite in March following: insomuch as that since that time she has not eaten nor drunk any thing at all, but only wetts her lips with a feather dipt in water. They were told also that her gutts (she alwayes keeps her bed) lye out by her at her fundament shrunken. Some of the neighbouring ministers visit her often: others that see her for curiosity give her mony, sixpence or a shilling, which she refuseth, and her mother taketh. But it does not appear they gain by it so much as to breed a suspition of a cheat. The woman is manifestly sick, and ’tis thought she cannot last much longer. Her talk (as the gentlewoman that went from this house told me) is most heavenly. To know the certainty, there bee many things necessary which cannot honestly be pryed into by a man. First, whether her gutts (as ’tis said) lye out. Secondly, whether any excrement pass that way, or none at all. For if it pass, though in small quantity, yet it argues food proportionable, which may, being little, bee given her secretly and pass through the shrunken intestine, which may easily be kept clean. Thirdly, whether no urine at all pass: for liquors also nourish as they go. I think it were somewhat inhumane to examin these things too nearly, when it so little concerneth the commonwealth: nor do I know of any law that authoriseth a Justice of peace, or other subject, to restrain the liberty of a sick person so farr as were needful for a discovery of this nature. I cannot therefore deliver any judgment in the case. The examining whether such a thing as this bee a miracle, belongs I think to the Church. Besides, I myself in a sickness have been without all manner of sustenance for more than six weeks together: which is enough to make mee think that six months would not have made it a miracle. Nor do I much wonder that a young woman of clear memory, hourely expecting death, should bee more devout then at other times. ’Twas my own case. That which I wonder at most, is how her piety without instruction should bee so eloquent as ’tis reported.

THO. HOBBES.

_Chatsworth, Oct. 20. 68._

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Footnote 6:

Amongst the MSS. of the Royal Society.

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VI.
LETTER TO MR. OLDENBURG.[7]

WORTHY S^R

In the last Transactions for September and October I find a letter addressed to you from D^r Wallis, in answer to my LUX MATHEMATICA. I pray you tell me that are my old acquaintance, whether it be (his words and characters supposed to be interpreted) intelligible. I know very well you understand sense both in Latine, Greeke, and many other languages. He shows you no ill consequence in any of my arguments. Whereas I say there is no proportion of _infinite_ to _finite_. He answers, he meant _indefinite_; but derives not his conclusion from any other notion than simply _infinite_. I said the root of a square number cannot be the length of the side of a square figure, because a root is part of a square number, but length is no part of a square figure. To which he answers nothing. In like manner, he shuffles off all my other objections, though he know well enough that whatsoever he has written in Geometry (except what he has taken from me and others) dependeth on the truth of my objections. I perceive by many of his former writings that I have reformed him somewhat as to the Principles of Geometry, though he thanke me not. He shuffles and struggles in vaine, he has the hooke in his guills, I will give him line enough: for (which I pray you tell him) I will no more teach him by replying to any thing he shall hereafter write, whatsoever they shall say that are confident of his Geometry. _Qui volunt decipi, decipiuntur._ He tells you that I bring but _crambe sæpe cocta_. For which I have a just excuse, and all men do the same; they repeat the same words often when they talk with them that cannot heare.

I desire also this reasonable favour from you: that, if hereafter I shall send you any paper tending to the advancement of physiques or mathematiques, and not too long, you will cause it to be printed by him that is printer to the Society, as you have done often for D^r Wallis: it will save me some charges.

I am, S^r,

Your affectionate frend and humble seruant

THOMAS HOBBES.

_November the 26th, 1672._

ffor my worthy and much honoured
frend M^r HENRY OLDENBURGH,
Secretary to the Royal Society.

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Footnote 7:

Amongst the MSS. of the Royal Society.

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VII.
TO THE RIGHT HONOURABLE
THE MARQUIS OF NEWCASTLE.[8]

The passions of man’s mind, except onely one, may bee observed all in other living creatures. They have desires of all sorts, love, hatred, feare, hope, anger, pitie, æmulation, and y^e like: onely of curiositie, which is y^e desire to know y^e causes of thinges, I never saw signe in any other living creature but in man. And where it is in man, I find alwaies a defalcation or abatement for it of another passion, which in beastes is commonly predominant, namely, a ravenous qualitie, which in man is called _avarice_. The desire of knowledge and desire of needlesse riches are incompatible, and destructive one of another. And therefore as in the cognitive faculties reason, so in the motive curiositie, are the markes that part y^e bounds of man’s nature from that of beastes. Which makes mee, when I heare a man, upon the discovery of any new and ingenious knowledge or invention, aske gravely, that is to say, scornefully, _what ’tis good for_, meaning what monie it will bring in, (when he knows as little, to one that hath sufficient what that overplus of monie is good for), to esteeme that man not sufficiently removed bn 484.png from brutalitie. Which I thought fit to say by way of anticipation to y^e grave scorners of philosophie, and that your lordship, after having performed so noble and honourable acts for defence of your countrie, may thinke it no dishonour in this unfortunate leasure to have employed some thoughts in the speculation of the noblest of the senses, _vision_.

That which I have written of it is grounded especially upon that w^{ch} about 16 yeares since I affirmed to your Lo^{PP} at Welbeck, that light is a fancy in the minde, caused by motion in the braine, which motion againe is caused by the motion of y^e parts of such bodies as we call _lucid_: such as are the sunne and y^e fixed stars, and such as here on earth is fire. By putting you in mind hereof, I doe indeed call you to witnesse of it: because, the same doctrine having since been published by another, I might bee challenged for building on another man’s ground. Yett philosophical ground I take to be of such a nature, that any man may build upon it that will, especially if the owner himselfe will nott. But upon this ground, with the helpe of some other speculations drawne from the nature of motion and action, I have, I thinke, derived y^e reason of all the phænomena I have mett with concerning light and vision, both solidly enough nott to be confuted, and withall easilie enough to be understood by such as can give that attention thereto which the figures, whereby such motion as causeth vision is described, do require. All that I shall bee ever able to adde to it, is polishing: for, being the first draught, it could nott bee so perfect as I hope hereafter to make it in Latin. Butt as it is, it will sufficiently give your Lo^{PP} satisfaction in those _quæres_ you were pleased to make concerning this subject. I am content that it passe, in respect of some drosse that yett cleaves to it, for ore: w^{ch} is much better than old ends raked out of the kennell of sophisters’ bookes. And for such I commend it to your Lo^p, and myselfe to your accustomed good opinion: which hath beene hitherto so greate honour to mee, as I am nott known to the world by any thing so much as by being,

My most noble lord,

Your Lo^{p’s} most humble

and most obliged servant

THO. HOBBES.

The treatise ends with the following passage:--

To conclude, I shall doe like those that build a new house where an
old one stood before, that is to say, carry away the rubbish.

And first, away goes the old opinion that the _shewes_ (which they
call visible species) of all objects, are in all places, and all the
babble _de extramittendo et intromittendo_. For their species are
nothing else but fancie, made by the light proceeding directly or by
repurcussion or refraction made from the object to y^e eye, and so
moving the braine and other parts within.

Secondly, the opinion which Vitellio takes for an axiome and
foundation of his _Catoptricques_, that y^e place of y^e image by
reflexion is in the perpendicular drawn from the object to the glasse.
For it is false both in plaine glasses and in sphæricall, whether
convexe or concave.

Thirdly, the opinion that light is engendred faster in hard bodies, as
glasse, than in thin and fluid, as aire.

Fourthly, that objects are seen by _penicilli_ that have their common
base in the pupills: for y^e center of y^e eye is in their common
base.

Fifthly, the opinion that there bee other visuali lines by which wee
see distinctly besides y^e optique axis.

Sixthly, the opinion that perspective glasses and amplifying glasses
are best made of hyperbolicall figures.

Seventhly, the opinion that light is a bodie, or any other such thing
than such light as wee have in dreames.

Eighthly, that y^e object appeares greater and lesse in ye same
proportion that y^e angles have under which they are seene.

Lastly, is to be cast away the conceipt of millions of strings in ye
optique nerve, by which the object playes upon the braine, and makes
y^e soule listen unto it, and other innumerable such trash.

How doe I feare that y^e attentive reader will find that which I have
delivered concerning y^e _Optiques_ fitt to bee cast outt as rubbish
among the rest. If hee doe, hee will recede from y^e authoritie of
experience, which confirmeth all I have said. Butt if it bee found
true doctrine, (though yett it wanteth polishing), I shall deserve the
reputation of having beene y^e first to lay the grounds of two
sciences; this of _Optiques_, y^e most curious, and y^t other of
_Natural Justice_, which I have done in my booke DE CIVE, y^e most
profitable of all other.

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Footnote 8:

Harleian MS. 3360: a treatise on Optics, entitled “A minute or first
draught of the Optiques. In two parts. By Thomas Hobbes. At Paris,
1646.” The second part, _On Vision_, we have in Latin, in the DE
HOMINE: the first, _On Illumination_, was never published. The
dedication to the Marquis of Newcastle, and the concluding paragraph,
is all that is here given of the treatise.

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VIII.
TO THE KING’S MOST EXCELLENT MAJESTY
THE HUMBLE PETITION OF THOMAS HOBBES[9]

Sheweth, that though your Majesty hath been pleased to take off the restraint of late years laid upon the pensions payable out of your privy purse, yet your Majesty’s Officers refuse to pay the pension of your petitioner without your Majesty’s express command.

And humbly beseaceth your Majesty, (considering his extreme age, perpetual infirmity, frequent and long sickness, and the aptness of his enemies to take any occasion to report that your petitioner by some ill behaviour hath forfeited your wonted favour), that you would be pleased to renew your order for the payment of it in such manner as to his great comfort he hath for many years enjoyed it.[10]

And daily prayeth to God Almighty to bless your Majesty with long life, constant health, and happinesse.

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Footnote 9:

Additional MSS. 4292. Brit. Mus.

Footnote 10:

Deinde redux mihi Rex concessit habere quotannis
Centum alias libras ipsius ex loculis:
Dulce mihi donum.
VITA _Carm. expres._ p. xcviii.

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END OF VOL. VII.

RICHARDS, PRINTER, 100, ST. MARTIN’S LANE.

------------------------------------------------------------------------

Transcriber’s Note

Some Greek passages employ the stigma ligature (‘st’). The available Unicode character (ϛ) is nearly indistinguishable from the final form of sigma (ς). Occasionally, the ‘ου’ ligature is employed. The only available character (ᴕ) is a Latin, not a Greek character. It is rendered here as ‘ου’. There were also a number of instances of improper placement of diacritical marks, particularly in cases where the breathing mark and accents appear on the first rather than the second of two leading vowels, e.g. ‘ὅυτως’ rather than ‘οὕτως’.

At 93.4, the response ‘No sure’ is obviously incorrect. It is most likely that it should have read ‘Not sure.’, but it may also have been an unfinished line.

Other errors deemed most likely to be the printer’s have been corrected, and are noted here. Given the age of the text, any corrections were made sparingly. The references are to the page and line in the original.

8.35 with increasing [s]wiftness? Restored. 12.34 being so very heavy[?] Added. 54.8 too much or too[l i/ li]ttle Replaced. 62. was to be demonst[r]ated. Inserted. 65.33 which is 72[.] Added. 67.1 and multip[l]ying lines Inserted. 72.5 and subtil doc[t]rines. Inserted. 74.1 who begi[u/n]s his history Inverted. 91.16 the space be[t]ween. Inserted. 91.18 whose tap[-]hole is very little Inserted. 96.5 and th[a/e]n H will be east Replaced. 114.27 a spring[ ]upon the top Inserted. 158.19 the air which[ which] was Redundant. 163.11 8 degrees 30 minutes[.]? Removed. 192.19 (called by him [ε/ἐ]φαρμόζοντα) Replaced. 200.5 may so precisely deter[ter]mine Removed. 206.1 lines whi[e/c]h shall never meet Replaced. 208.10 [ὅυ/οὕ]τως ἔχει Replaced. 208.13 [ὅυ/οὕ]τως ἔχει Replaced. 225.8 as by raref[r]action and condensation. Removed. 263.17 [“]_The magnitude of an angle_ Added. 277.33 th[e/a]n of one in nine? Replaced. 297.26 At the seventee[n]th chapter Inserted. 300.22 _that of G K to G [E,/E.]_” Replaced. 323.7 _tanquam dicta problematicè._[”] Added. 338.31 and so mis[s]pend it? Inserted. 351.16 by which you live[,/.] Replaced. 376.4 _propositione præcedente._[”] Added. 376.22 it shall quite vanish. [And so] Missing? 342.12 to the present purpose[)]. Added (likely). 382.12 whether διπλάσιος and διπλασ[ι]ίων be one Removed. 391.5 by the word Σημ[~ε/εῖ]ον in Euclid Replaced. 412.17 κα[ι/ὶ] ἡ Ἔμπουσα Replaced. 413.26 τῶν θεῶν [Α/Ἀ]ιγύπτιοι Replaced. 413.27 κα[ἱ/ὶ] ἅτε Ἀιγύπτιος, Replaced. 413.30 ποδῶν [ὴ/ἠ]δέ κνημάων Replaced. 414.1 ῥᾳδίως[ ]ἔγνων ὑπολαμβάνοντες. Inserted. 414.4 ἀλλὰ κατὰ ῥύμην [ὰ/ἀ]έριον Replaced. 415.23 deriveth it [τ/π]αρὰ τὸ ἐμποδιζειν Replaced. 415.25 it saith, [Ἕ/Ἔ]μπουσα Ψιλοῦπαι Replaced. 415.33 some had no legs, &c[.] Added. 416.7 τύχη [ὲ/ἐ]μποδιζουσα Replaced. 416.16 [Ἕ/Ἔ]μποῦσα is also a name for Lamia Replaced. 418.16 [ὁι/οἱ] δὲ ὑπέφευγον Transposed. 418.20 καὶ τὸ [ὲ/ἐ]πιπηδᾶν Replaced. 419.13 γαρ [ὅι/οἵ]νου πληροῦντες, Replaced. 419.14.1 εἶχε τὸν [ὅι/οἵ]νου. Replaced. 419.14.2 [Α/Ἀ]σκωλιάζειν Replaced. 423.1 καὶ ζώων παντοδαπῶν [ἐι/εἰ]κόσι Replaced. 455.27 two spaces th[e/a]n when double Replaced. 456.3 a pound two foote a[t] the rate of Added. 456.6 rate of a mile an how[er/re] Transposed.