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.

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.