Aristotle’s speculative Idea is chiefly to be gathered from his Metaphysics, especially from the last chapters of the twelfth book (Λ) which deal with the divine Thought. But this treatise has the peculiar drawback noticed above (p. 128) of being a compilation, several treatises having been combined into one. Aristotle and the ancients did not know this work by the name of the Metaphysics; it was by them called πρώτη φιλοσοφία.[87] The main portion of this treatise has a certain appearance of unity given to it by the connection of the argument,[88] but it cannot be said that the style is orderly and lucid. This pure philosophy Aristotle very clearly distinguishes (Metaph. IV. 1) from the other sciences as “the science of that which is, in so far as it is, and of what belongs to it implicitly and explicitly.” The main object which Aristotle has in view (Metaph. VII. 1) is the definition of what this substance (οὐσία) really is. In this ontology or, as we call it, logic, he investigates and minutely distinguishes four principles (Metaph. I. 3): first, determination or quality as such, the wherefore of anything, essence or form; secondly, the matter; thirdly, the principle of motion; and fourthly, the principle of final cause, or of the good. In the later part of the Metaphysics Aristotle returns repeatedly to the determination of the Ideas, but here also a want of connection of thought appears, even though all is subsequently united into an entirely speculative Notion. To proceed, there are two leading forms, which Aristotle characterizes as that of potentiality (δύναμις) and that of actuality (ἐνέργεια); the latter is still more closely characterized as entelechy (ἐντελεχεια) or free activity, which has the end (τὸ τέλος) in itself, and is the realization of this end. These are determinations which occur repeatedly in Aristotle, especially in the ninth book of the Metaphysics, and which we must be familiar with, if we would understand him. The expression δύναμις is with Aristotle the beginning, the implicit, the objective; also the abstract universal in general, the Idea, the matter, which can take on all forms, without being itself the form-giving principle. But with an empty abstraction such as the thing-in-itself Aristotle has nothing to do. It is first in energy or, more concretely, in subjectivity, that he finds the actualizing form, the self-relating negativity. When, on the other hand, we speak of Being, activity is not yet posited: Being is only implicit, only potentiality, without infinite form. To Aristotle the main fact about Substance is that it is not matter merely (Metaph. VII. 3); although in ordinary life this is what is generally taken to be the substantial. All that is contains matter, it is true, all change demands a substratum (ὑποκείμενον) to be affected by it; but because matter itself is only potentiality, and not actuality—which belongs to form—matter cannot truly exist without the activity of form (Metaph. VIII. 1, 2).