Scanned, proofed and corrected from the original hardcover edition for enjoyable reading. (Worth every penny spent!)
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An excerpt from the beginning:
THE WORLD; or, Essay On Light*
CHAPTER I.
Of the difference between our sensations and the things which produce them.
PROPOSING, as I do, to treat of the nature of light, the first thing of which I wish you to take note is, that there may be a difference between the sensation which we have in ourselves, that is to say, the idea which is formed within our imagination by the help of our eyes, and that which exists in the objects that produce within us the sensation, namely, that which exists in the flame, or in the sun, and is called by the name of light ; because, although everyone is commonly persuaded that the ideas that we have in our thought are altogether similar to the objects whence they proceed, I see no reason, nevertheless, to assure us that this is true ; but, on the contrary, I observe many facts which should incline us to question it.
* This is a fragment of the Treatise referred to in the "Discourse on Method" as having been suppressed by the author.
You know that words, while having no resemblance to the things which they signify, do not fail to make them intelligible to us, and often, even without our paying attention to the sound of the words, or to their syllables; so that it may happen that after having listened to a discourse, the meaning of which we have
completely understood, we are not able to say in what language it was spoken. But if words, which signify nothing except by human institution, are capable of making conceivable for us things to which they have no resemblance, why may not nature also have established a certain sign which should make us feel the sensation of light, although this sign should have nothing in itself resembling sensation? Has she not thus appointed laughter and tears to make us read joy and sadness in the human countenance?
But you will say, perhaps, that our ears make us perceive in reality merely the sound of the words, and our eyes only the face of him who laughs or who weeps, and that it is our mind, which, having retained what these words and this countenance signify, represents it to us at the same time. To that I may reply that, just in the same way, it is our mind which represents to us the idea of light whenever the action which signifies it touches our eye; but, without wasting time in dispute, I will at once bring forward another illustration.
Do you think that when we pay no attention to the meaning of words, and only hear the sound of them, that the idea of this sound, which is formed within our thought, is anything like the object which is the cause of it? A man opens his mouth, moves his tongue, expels his breath; I see nothing in all these motions which is not quite different from the idea of the sound which they cause us to imagine. And most philosophers assure us that the sound is nothing but a certain trembling of the air which has just struck our ears ; so that, if the sense of hearing brought to our thought the true image of its object, it would be necessary, in place of making us conceive the sound, that it should make us conceive the motion of the portions of the air which is trembling at the time against our ears. But because, perhaps, everybody will not believe what the philosophers say, I will adduce still another example. Touch is the one of all the senses which we consider the least deceptive and the most trustworthy ; so that, if I prove to you that even touch makes us conceive many ideas which do not at all resemble the objects which produce them, I do not think you ought to consider it strange if I say that sight may do the same.
