The highest conception of all was apparently by the older Stoics declared to be the conception of Being. Since, however, speaking strictly, only what is material can be said to have any being, and many of our notions refer to incorporeal and therefore unreal objects, the conception of Something [178] was in later times put in the place of the conception of Being. This indefinite Something comprehends alike what is material and what is not material—in other words, what has being and what has not being; and the Stoics appear to have made this contrast the basis of a real division of things. [179] When it becomes a question, however, of formal elementary conceptions or categories, other points are emphasised which have no connection with the division into things material and things not material. Of this kind are the four highest conceptions, [180]—all subordinate to the conception of Something, viz. subject-matter or substance (τὸ ὑποκείμενον) property or form (τὸ ποιὸν), variety (τὸ πὼς ἔχον), and variety of relation (τὸ πρός τί πως ἔχον). [181] [(β) Category of subject-matter or substance.] The first of these categories [182] denotes the subject-matter of things in themselves (τὸ ὑποκείμενον), the material of which they are made, irrespective of any and every quality, [183] the something which underlies all definite being, and which alone has a substantial value. [184] Following Aristotle, the Stoics distinguish, [185] in this category of matter, between matter in general, or universal matter, and the particular matter or material out of which individual things are made. The former alone is incapable of being increased or diminished. Far otherwise is the material of which particular things are made. This can be increased and diminished, and, indeed, is ever undergoing change; so much so, that the only feature which continues the same during the whole term of its existence [186] and constitutes its identity, is its quality. [(γ) The category of property.]