ere glance at fossil species shows us that life need not
have evolved at all, or might have evolved only in very restricted
limits, if it had chosen the alternative, much more convenient to
itself, of becoming anchylosed in its primitive forms. Certain
Foraminifera have not varied since the Silurian epoch. Unmoved witnesses
of the innumerable revolutions that have upheaved our planet, the
Lingulae are to-day what they were at the remotest times of the
paleozoic era.

The truth is that adaptation explains the sinuosities of the movement of
evolution, but not its general directions, still less the movement
itself.[51] The road that leads to the town is obliged to follow the ups
and downs of the hills; it _adapts itself_ to the accidents of the
ground; but the accidents of the ground are not the cause of the road,
nor have they given it its direction. At every moment they furnish it
with what is indispensable, namely, the soil on which it lies; but if we
consider the whole of the road, instead of each of its parts, the
accidents of the ground appear only as impediments or causes of delay,
for the road aims simply at the town and would fain be a straight line.
Just so as regards the evolution of life and the circumstances through
which it passes--with this difference, that evolution does not mark out
a solitary route, that it takes directions without aiming at ends, and
that it remains inventive even in its adaptations.

But, if the evolution of life is something other than a series of
adaptations to accidental circumstances, so also it is not the
realization of a plan. A plan is given in advance. It is represented, or
at least representable, before its realization. The complete execution
of it may be put off to a distant future, or even indefinitely; but the
idea is none the less formulable at the present time, in terms actually
given. If, on the contrary, evolution is a creation unceasingly renewed,
it creates, as it goes on, not only the forms of life, but the ideas
that will enable the intellect to understand it, the terms which will
serve to express it. That is to say that its future overflows its
present, and can not be sketched out therein in an idea.

There is the first error of finalism. It involves another, yet more
serious.

If life realizes a plan, it ought to manifest a greater harmony the
further it advances, just as the house shows better and better the idea
of the architect as stone is set upon stone. If