Sensations differing in time are two, and may differ without violating any law. In marking the fact that when we say two men perceive the same thing we do not mean that the immediate object of knowledge is in the two cases strictly one, but merely that these two objects are related in a peculiar way, Aristotle draws the line between sameness in sense first and in sense sixth. As to sense seventh. He distinguishes between the apparent and the real, and yet goes on speaking, quite in modern fashion, as though one thing could serve for both. He points out, _à propos_ of pressing upon the eyeball and doubling the visual image, that there is a distinction between the apparent and the real, and then closes the paragraph with the remark that "to those persons who do not move their organ of vision that which is one appears one."[41] This language would certainly seem to indicate that that which is appears--or that they are the same in some strict sense of the word. The sentence reads much in the style of Mr. Spencer or Sir William Hamilton. [37] Metaph. III, c. 5, § 10; c. 6, § 3. [38] _Ibid._ III, c. 2, § 6; IV, c. 6, § 1, and c. 9, § 1. [39] _Ibid._ IV, c. 9, § 1, and c. 6. [40] _Ibid._ III, c. 5, § 10; X, c. 6, § 6. [41] Metaph. X, c. 6, § 2. It appears, then, that Aristotle recognized a sameness in which there is no sense of duality, and samenesses in which two things are called the same and yet distinguished as two. Our way of expressing strict identity, however, a way which, as I have shown, does not properly express it all--seems to have misled him into finding a sort of quasi duality even here, where he knows it to be really absent. In a chapter[42] devoted to sameness and diversity, he closes his list of samenesses with the remark: "It is plain that sameness is a oneness either of two or more things with reference to their essence, or of one thing treated as two; as when you say a thing is the same with itself, for then you do treat it as two." We do employ two words, undoubtedly; but if we are really thinking a thing as itself, we are not making it dual in any sense whatever. The quotation smacks just a little of Cratylus. [42] _Ibid._ IV, c. 9. SEC. 27. The sceptical arguments of Pyrrho are excellent instances of a confusion of samenesses. The argument, for example, that since an apple seen by the eye as yellow seems to the taste sweet, and to the smell as fragrant, "that which is seen is just as likely to be something else as the reality;"[43] this argument gains what little plausibility it may have from the assumption that an object seen and an object tasted are (or ought to be) the same in sense first instead of sense third. [43] Diogenes Laërtius. IX, 9.