Good, as the universal end, the substantial foundation, and maintains this position against Heraclitus and the Eleatics. The Becoming of Heraclitus is a true and real determination, but change yet lacks the determination of identity with itself, the constancy of the universal. The stream is ever changing, yet it is nevertheless ever the same, and is really a universal existence. From this it is at once evident that Aristotle (Metaph. IV. 3-6) is controverting the opinions of Heraclitus and others when he says that Being and non-being are not the same (Vol. I. p. 282), and in connection with this lays down the celebrated maxim of contradiction, that a man is not at the same time a ship. This shows at once that Aristotle does not understand by this pure Being and non-being, this abstraction which is really only the transition of the one into the other; but by that which is, he understands Substance, the Idea, Reason, viewed likewise as an impelling end. As he maintains the universal against the principle of mere change, he puts forward activity in opposition to the numbers of the Pythagoreans, and to the Platonic Ideas. However frequently and fully Aristotle controverts both of these, all his objections turn on the remark already quoted (Vol. I. p. 213) that activity is not to be found in these principles, and that to say that real things participate in Ideas is empty talk, and a poetic metaphor. He says also that Ideas, as abstract universal determinations, are only as far as numbers go equal to things, but are not on that account to be pointed out as their causes. Moreover, he maintains that there are contradictions involved in taking independent species, since in Socrates, for instance, there are several ideas included: man, biped, animal (Metaph. I. 7 and 9). Activity with Aristotle is undoubtedly also change, but change that is within the universal, and that remains self-identical; consequently a determination which is self-determination, and therefore the self-realizing universal end: in mere alteration, on the contrary, there is not yet involved the preservation of identity in change. This is the chief point which Aristotle deals with. Aristotle distinguishes various moments in substance, in so far as the moments of activity and potentiality do not appear as one, but still in separation. The closer determination of this relation of energy to potentiality, of form to matter, and the movement of this opposition, gives the different modes of substance. Here Aristotle enumerates the substances; and to him they appear as a series of different kinds of substance, which he merely takes into consideration one by one, without bringing them together into a system. The three following are the chief among these:—