§ 60. To Thales, one of the Seven Wise Men of Greece, is commonly awarded the honor of being the founder of European philosophy. If he deserve this distinction, it is on account of the question which he raised, and not on account of the answer which he gave to it. Aristotle informs us that Thales held "water" to be "the material cause of all things."[157:9] This crude theory is evidently due to an interest in the totality of things, an interest which is therefore philosophical. But the interest of this first philosopher has a more definite character. It looks toward the definition in terms of some single conception, of _the constitution_ of the world. As a child might conceivably think the moon to be made of green cheese, so philosophy in its childhood thinks here of all things as made of water. Water was a well-known substance, possessing well-known predicates. To define all nature in terms of it, was to maintain that in spite of superficial differences, all things have these predicates in common. They are the predicates which qualify for reality, and compose a community of nature from which all the individual objects and events of nature arise. The successors of Thales were evidently dissatisfied with his fundamental conception, because of its lack of generality. They seized upon vaguer substances like air and fire, for the very definiteness of the nature of water forbids the identification of other substances with it. But what is so obviously true of water is scarcely less true of air and fire; and it appeared at length that only a substance possessing the most general characters of body, such as shape, size, and mobility, could be thought as truly primeval and universal. In this wise a conception like our modern physical conception of matter came at length into vogue. Now the problem of which these were all tentative solutions is, in general, the problem of _metaphysics_; although this term belongs to a later era, arising only from the accidental place of the discussion of first principles _after physics_ in the system of Aristotle. _The attempt to secure a most fundamental conception which attaches some definite meaning to the reality including and informing every particular thing, is metaphysics._ [Sidenote: Monism and Pluralism.]