n experience. They
represent a normal differentiation of interest which the individual
mind, in the course of its own thinking, tends to follow. It is true
that it can never be said with assurance that any age is utterly blind
to any aspect of experience. This is obviously the case with the
practical and theoretical interests which have just been distinguished.
There is no age that does not have some practical consciousness of the
world as a whole, nor any which does not seek more or less earnestly to
universalize its science. But though it compel us to deal abstractly
with historical epochs, there is abundant compensation in the
possibility which this method affords of finding the divisions of
philosophy in the manifestation of the living philosophical spirit.

[Sidenote: Metaphysics Seeks a Most Fundamental Conception.]

Sect. 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