y which must underlie the infinite diversity of experience.

Such, indeed, seems to us the present position of Metaphysics; and, what
is more important, it appears to react with increasing force upon the
theories and investigations of Science.

The problem of Reality is thus at present not without a special and
increasing interest for the students of Physical Science. Until lately
they have been taught and have always maintained that Matter is the
direct object of sense-perception. No doubt it is long since Philosophy
has urged that our conceptions of the external world are a mentally
constructed system. But this doctrine has made but little impression
upon the students of Natural Science. The objective origin of our
sensations and the apparently objective reality also of the intelligible
qualities and operative laws of the external world are too strongly
impressed upon their minds. Idealism and Transcendentalism have carried
no conviction to them. Still, the difficulties of common sense have
continued to grow. Recent developments of scientific theory have
increased the urgency of the problem, but they seem to us also to
suggest a solution the beneficial results of which affect the whole of
Metaphysics.

We refer to the doctrine of Energy, which occupies now as great a place
in the physical sciences as the doctrine of Evolution does in the
zoological sciences.

Natural philosophers have for some time taught that there are two Real
Things in the physical universe--Matter and Energy. It seems a very
striking theory. Has it received the attention it deserves from the
student of Metaphysics? We are convinced that it has not: and the reason
he most frequently gives for this neglect is that, being a purely
scientific doctrine, it does not come within his sphere. Science, we are
told, deals with the phenomenal world internally considered; Philosophy
with the relations of the phenomenal world to Reality, and with the
nature of the transcendental elements in our Knowledge.

This may be generally true. Nevertheless, Philosophy and Science have
surely concepts in common. They both refer to the same thing when they
speak of Space; we presume also when they speak of Matter. Indeed,
Philosophy analyses the conceptions involved not only in scientific
reasoning, but in the most common and ordinary mental processes. It
analyses them with special reference to the relations between the
Phenomenal and the Real--a question which, thoug