Thomas Hobbes

“ Now the interior coat of the eye is nothing else but a piece of the optic nerve, and therefore the motion is still continued thereby into the brain, and by resistance or reaction of the brain, is also a rebound in the optic nerve again, which we not conceiving as motion or rebound from within, think it is without, and call it light; as hath been already shewed by the experience of a stroke. We have no reason to doubt, that the fountain of light, the sun, worketh any other wise than the fire, at least in this matter, and thus all vision hath its original from such motion as is here described. ”

“ Nothing can make any thing in itself: the clapper hath not sound in it, but motion, and maketh motion in the internal parts of the bell so the bell hath motion, and not sound. That imparteth motion to the air; and the air hath motion, but not sound. The air imparteth motion by the ear and nerves to the brain; and the brain hath motion but not sound. From the brain it reboundeth back into the nerves outward, and thence it becometh an apparition without, which we call sound. ”

“ As colour is not inherent in the object, but an effect thereof upon us, caused by such motion in the object, as hath been described: so neither is sound in the thing we hear, but in ourselves. One manifest sign thereof is: that as a man may see, so also he may hear double or treble, by multiplication of echoes, which echoes are sounds as well as the original; and not being in one and the same place, cannot be inherent in the body that maketh them. ”

“ Originally all conceptions proceed from the actions of the thing itself, whereof it is the conception. Now when the action is present, the conception it produceth is called SENSE, and the thing by whose action the same is produced is called the OBJECT of sense. ”

“ For the third, we are to consider first, that upon every great agitation or concussion of the brain, as it happeneth from a stroke, especially if the stroke be upon the eye, whereby the optic nerve suffereth any great violence, there appeareth before the eyes a certain light, which light is nothing without, but an apparition only, all that is real being the concussion or motion of the parts of that nerve. ”

“ From which experience we may conclude, that apparition of light without, is really nothing but motion within. If therefore from lucid bodies there can be derived motion, so as to affect the optic nerve in such manner as is proper thereunto, there will follow an image of light somewhere in that line by which the motion was last derived unto the eye ”

“ But because it may be said that notwithstanding the image in the water be not in the object, but a thing merely phantastical, yet there may be colour really in the thing itself; I will urge further this experience: that divers times men see directly the same object double, as two candles for one, which may happen by distemper, or otherwise without distemper if a man will, the organs being either in their right temper, or equally distempered. ”

“ So likewise the heat we feel from the fire is manifestly in us, and is quite different from the heat that is in the fire. For our heat is pleasure or pain, according as it is extreme or moderate; but in the coal there is no such thing. By this the fourth and last of the propositions is proved (viz.) That as in conception by vision, so also in the conceptions that arise from other senses, the subject of their inherence is not the object, but the sentient. ”

“ And to proceed to the rest of the senses, it is apparent enough, that the smell and taste of the same thing, are not the same to every man, and therefore are not in the thing smelt or tasted, but in the men. ”

“ Secondly, that the image of any thing seen by reJection in glass or water or the like, is not any thing in or behind the glass, or in or under the water, every man may prove to himself; which is the second proposition. ”