chief errors that can be committed in science for men to fancy that they can define that which they can only conceive, and distinguish what is clear in it from what is obscure, while they do not see the difference between that which must be defined before it is understood and that which can be fully known by itself. Now, among things which can thus be clearly known by themselves, we must put doubting, thinking, being. For I do not believe any one ever existed so stupid as to need to know what being is before he could affirm that he is; and it is the same of thought and doubt. Nor can he learn these things except by himself, nor be convinced of them but by his own experience, and by that consciousness and inward witness which every man finds in himself when he examines the subject. And as we should define whiteness in vain to a man who can see nothing, while one can open his eyes and see a white object requires no more, so to know what doubting is, and what thinking is, it is only necessary to doubt and to think.”[251] Nothing could more tend to cut short the verbal cavils of the schoolmen, than this limitation of their favourite exercise, definition. It is due, therefore, to Descartes, so often accused of appropriating the discoveries of others, that we should establish his right to one of the most important that the new logic has to boast. [250] Dissertation, ubi, suprá, Stewart, in his Philosophical Essays, note A, had censured Reid for assigning this remark to Descartes and Locke, but without giving any better reason than that it is found in a work written by Lord Stair; earlier, certainly, than Locke, but not before Descartes. It may be doubtful, as we shall see hereafter, whether Locke has not gone beyond Descartes, or at least distinguished undefinable words more strictly. [251] Vol. xi., p. 369. |His notion of substances.| 102. He seems, at one moment, to have been on the point of taking another step very far in advance of his age. “Let us take,” he says, “a piece of wax from the honey-comb; it retains some taste and smell, it is hard, it is cold, it has a very marked colour, form, and size. Approach it to the fire; it becomes liquid, warm, inodorous, tasteless; its form and colour are changed, its size is increased. Does the same wax remain after these changes? It must be allowed that it does; no one doubts it, no one thinks otherwise. What was it then that we so distinctly knew to exist in this piece of wax? Nothing certainly that we observed by the senses, since all that the taste, the smell, the sight, the touch reported to us has disappeared, and still the same wax remains.” This something which endures under every change of sensible qualities cannot be imagined; for the imagination must represent some of these qualities, and none of them are essential to the thing; it can only be conceived by the understanding.[252] [252] Méditation Seconde, i. 256. |Not quite correct.|