t of human
reflective thought was to discover the _Welt-stoff_--the
substance which underlies all modes and forms of existence,
and that man was regarded as an integral and organic part of the
whole.

Greek philosophy, which started with these crude, but brilliant
speculations, had developed a wonderful variety and subtlety,
when Plato, animated by the same desire to discover the Ground
of things, introduced his doctrine of Ideas. He held that bodies
are not, in themselves, the true reality; they are manifestations
of something else. Reality, for him, is a system of real thoughts
which he calls Ideas, and the world of objects gets its reality by
participating in them or by copying them. The senses, under
such conditions, cleave to the copies, whereas the mind, in
thinking by general ideas, apprehends the true reality. These
ideas must not be regarded as mere products of the mind, but as
real existences, which, when manifested under conditions of
time and space, multiply themselves in innumerable objects. In
fact, so real are they that without them there would be no
objects at all.

Schopenhauer adopted this doctrine of Ideas, and brought it into
connection with his characteristic theory of Will as the ultimate
Ground. The Ideas, for him, represent definite forms of
existence, manifested in individual things and beings. There are
thus, he said, Ideas of the simple elementary forces of nature,
such as gravity and impenetrability; there are Ideas of the
different forms of individual things; and there are Ideas of the
different species of organic beings, including man. He followed
Plato in refusing any true reality to individual objects and
separated the Idea from its sensuous form. "By Idea, then" (he
writes), "I understand every definite and fixed grade of the
objectification of will, so far as it is a thing-in-itself, and
therefore has no multiplicity. These grades are related to
individual things as their eternal forms or prototypes." Hence,
the world known to the senses could be nothing other than mere
phenomenal appearance.

Now it is manifestly an enormous stride in the direction of
Nature Mysticism to recognise in material objects a factor, or
element, which is akin to the highest activities of the human
mind. But, as already stated, in expounding the view known as
Ideal-Realism, the nature-mystic cannot be content to stop here.
Nor indeed was Schopenhauer consistent in stopping here. If he
had been faithful