It is not possible in such a work as this, to give a carefully reasoned proof of this view of the relation of thought and things, or to repeat the argument of Kant.  I must be content with merely referring to it, as showing that the principles in virtue of which we think, are the principles in virtue of which objects as we know them exist; and we cannot be concerned with any other objects.  The laws which scientific investigation discovers are not only ideas that can be written in books, but also principles which explain the nature of things.  In other words, the hypotheses of the natural sciences, or their categories, are points of view in the light of which the external world can be regarded as governed by uniform laws.  And these constructive principles, which lift the otherwise disconnected world into an intelligible system, are revelations of the nature of intelligence, and only on that account principles for explaining the world.

                           “To know,
  Rather consists in opening out a way
  Whence the imprisoned splendour may escape,
  Than in effecting entry for a light
  Supposed to be without."[A]

[Footnote A:  Paracelsus.]

In this sense, it may be said that all knowledge is anthropomorphic; and in this respect there is no difference between the physics, which speaks of energy as the essence of things, and the poetry, which speaks of love as the ultimate principle of reality.  Between such scientific and idealistic explanations there is not even the difference that the one begins without and the other within, or that the one is objective and the other subjective.  The true distinction is that the principles upon which the latter proceed are less abstract than those of science.  “Reason” and “love” are higher principles for the explanation of the nature of things than “substance” or “cause”; but both are forms of the unity of thought.  And if the latter seem to have nothing to do with the self, it is only because they are inadequate to express its full character.  On the other hand, the higher categories, or ideas of reason, seem to be merely anthropomorphic, and, therefore, ill-suited to explain nature, because the relation of nature to intelligence is habitually neglected by ordinary thought, which has not pressed its problems far enough to know that such higher categories can alone satisfy the demand for truth.

But natural science is gradually driven from the lower to the higher categories, or, in other words, it is learning to take a more and more idealistic view of nature.  It is moving very slowly, because it is a long labour to exhaust the uses of an instrument of thought; and it is only at great intervals in the history of the human intellect, that we find the need of a change of categories.  But, as already hinted, there is no doubt that science is becoming increasingly aware of the conditions, under which alone its results may be held as valid.  At first, it drove “mind”