"It is evident," as Hobbes remarks,[15] "that truth and falsity have no place but amongst such living creatures as use speech. For though some brute creatures, looking upon the image of a man in a glass, may be affected with it, as if it were the man himself, and for this reason fear it or fawn upon it in vain; yet they do not apprehend it as true or false, but only as like; and in this they are not deceived. Wherefore, as men owe all their true ratiocination to the right understanding of speech, so also they owe their errors to the misunderstanding of the same; and as all the ornaments of philosophy proceed only from man, so from man also is derived the ugly absurdity of false opinion. For speech has something in it like to a spider's web (as it was said of old of Solon's laws), for by contexture of words tender and delicate wits are ensnared or stopped, but strong wits break easily through them." Let me illustrate my meaning by at least one instance. Among the words which have proved spider's webs, ensnaring even the greatest intellects of the world from Aristotle down to Leibniz, the terms _genus_, _species_, and _individual_ occupy a very prominent place. The opposition of Aristotle to Plato, of the Nominalists to the Realists, of Leibniz to Locke, of Herbart to Hegel, turns on the true meaning of these words. At school, of course, all we can do is to teach the received meaning of _genus_ and _species_; and if a boy can trace these terms back to Aristotle's γένος and εἶδος, and show in what sense that philosopher used them, every examiner would be satisfied. But the time comes when we have to act as our own examiners, and when we have to give an account to ourselves of such words as _genus_ and _species_. Some people write, indeed, as if they had seen a _species_ and a _genus_ walking about in broad daylight; but a little consideration will show us that these words express subjective concepts, and that, if the whole world were silent, there would never have been a thought of a _genus_ or a _species_. There are languages in which we look in vain for corresponding words; and if we had been born in such a language, these terms and thoughts would not exist for us. They came to us, directly or indirectly, from Aristotle. But Aristotle did not invent them, he only defined them in his own way, so that, for instance, according to him, all living beings would constitute a _genus_, men a _species_, and Socrates an _individual_.