Therefore, in attempting to construct a theory of the universe they commenced by postulating an ἀρχή--a first principle or element out of which, by a _vital_ process, all else should be produced. "Accordingly, whatever seemed the most subtle or pliable, as well as _universal_ element in the mass of the visible world, was marked as the seminal principle whose successive developments and transformations produced all the rest."[402] With this seminal principle the living, _animating_ principle seems to have been associated--in some instances perhaps confounded, and in most instances called by the same name. And having pursued this analogy so far, we shall find the _most decided and conclusive_ evidence of a tendency to regard the soul of man as similar, in its nature, to the soul which animates the world. [Footnote 401: Plato's "Laws," bk. x. ch. i.; "Timæus," ch. xii.] [Footnote 402: Butler's "Lectures on Ancient Philosophy," vol. 1. p. 292.] _Thales of Miletus_(B.C. 636-542) was the first to lead the way in the perilous inquiry after an ἀρχή, or first principle, which should furnish a rational explanation of the universe. Following, as it would seem, the genealogy of Hesiod, he supposed _water_ to be the primal element out of which all material things were produced. Aristotle supposes he was impressed with this idea from observing that all things are nourished by moisture; warmth itself, he declared, proceeded from moisture; the seeds of all things are moist; water, when condensed, becomes earth. Thus convinced of the universal presence of water, he declared it to be the first principle of things.[403] And now, from this brief statement of the Thalean physics, are we to conclude that he recognized only a _material_ cause of the universe? Such is the impression we receive from the reading of the First Book of Aristotle's Metaphysics. His evident purpose is to prove that the first philosophers of the Ionian school did not recognize an _efficient_ cause. In his opinion, they were decidedly materialistic. Now to question the authority of Aristotle may appear to many an act of presumption. But Aristotle was not infallible; and nothing is more certain than that in more than one instance he does great injustice to his predecessors.[404] To him, unquestionably, belongs the honor of having made a complete and exhaustive classification of causes, but there certainly does appear something more than vanity in the assumption that he, of all the Greek philosophers, was the only one who recognized them all. His sagacious classification was simply a resumè of the labors of his predecessors. His "principles" or "causes" were incipient in the thought of the first speculators in philosophy. Their accurate definition and clearer presentation was the work of ages of analytic thought. The phrases "efficient," "formal," "final" cause, are, we grant, peculiar to Aristotle; the ideas were equally the possession of his predecessors.