out of time. History, on the other hand, aims at no more than the
generalized description of one or another phase of a time-process.
To this it may be replied that physics, and physics only, answers to
this altogether too narrow conception of science. The laws of matter
in motion are, or seem to be, of the timeless or mathematical kind.
Directly we pass on to biology, however, laws of this kind are not
to be discovered, or at any rate are not discovered. Biology deals
with life, or, if you like, with matter as living. Matter moves. Life
evolves. We have entered a new dimension of existence. The laws of
matter in motion are not abrogated, for the simple reason that in
physics one makes abstraction of life, or in other words leaves its
peculiar effects entirely out of account. But they are transcended.
They are multiplied by _x_, an unknown quantity. This being so from
the standpoint of pure physics, biology takes up the tale afresh, and
devises means of its own for describing the particular ways in which
things hang together in virtue of their being alive. And biology finds
that it cannot conveniently abstract away the reference to time. It
cannot treat living things as machines. What does it do, then? It takes
the form of history. It states that certain things have changed in
certain ways, and goes on to show, so far as it can, that the changes
are on the whole in a certain direction. In short, it formulates
tendencies, and these are its only laws. Some tendencies, of course,
appear to be more enduring than others, and thus may be thought to
approximate more closely to laws of the timeless kind. But _x_, the
unknown quantity, the something or other that is not physical, runs
through them all, however much or little they may seem to endure. For
science, at any rate, which departmentalizes the world, and studies
it bit by bit, there is no getting over the fact that living beings
in general, and human beings in particular, are subject to an evolution
which is simple matter of history.