that its constancy, in his opinion, was the
source of all natural as well as moral laws. Had he doubted for a moment
the stability of human nature, the foundations of his system would have
fallen out; the forms of perception and thought would at once have lost
their boasted necessity, since to-morrow might dawn upon new categories
and a modified _a priori_ intuition of space or time; and the avenue
would also have been closed by which man was led, through his
unalterable moral sentiments, to assumptions about metaphysical truths.

[Sidenote: Contrary currents of opinion.]

[Sidenote: Evolution]

The force of this long tradition has been broken, however, by two
influences of great weight in recent times, the theory of evolution and
the revival of pantheism. The first has reintroduced flux into the
conception of existence and the second into the conception of values. If
natural species are fluid and pass into one another, human nature is
merely a name for a group of qualities found by chance in certain tribes
of animals, a group to which new qualities are constantly tending to
attach themselves while other faculties become extinct, now in whole
races, now in sporadic individuals. Human nature is therefore a
variable, and its ideal cannot have a greater constancy than the demands
to which it gives expression. Nor can the ideal of one man or one age
have any authority over another, since the harmony existing in their
nature and interests is accidental and each is a transitional phase in
an indefinite evolution. The crystallisation of moral forces at any
moment is consequently to be explained by universal, not by human, laws;
the philosopher's interest cannot be to trace the implications of
present and unstable desires, but rather to discover the mechanical law
by which these desires have been generated and will be transformed, so
that they will change irrevocably both their basis and their objects.

[Sidenote: Pantheism.]

To this picture of physical instability furnished by popular science are
to be added the mystical self-denials involved in pantheism. These come
to reinforce the doctrine that human nature is a shifting thing with the
sentiment that it is a finite and unworthy one: for every determination
of being, it is said, has its significance as well as its origin in the
infinite continuum of which it is a part. Forms are limitations, and
limitations, according to this philosophy, would be defects, so that
man'