be easy
afterwards to soften the outlines and to correct what is too geometrical
in the drawing--in short, to replace the rigidity of a diagram by the
suppleness of life.

* * * * *

To what date is it agreed to ascribe the appearance of man on the earth?
To the period when the first weapons, the first tools, were made. The
memorable quarrel over the discovery of Boucher de Perthes in the quarry
of Moulin-Quignon is not forgotten. The question was whether real
hatchets had been found or merely bits of flint accidentally broken. But
that, supposing they were hatchets, we were indeed in the presence of
intelligence, and more particularly of _human_ intelligence, no one
doubted for an instant. Now let us open a collection of anecdotes on the
intelligence of animals: we shall see that besides many acts explicable
by imitation or by the automatic association of images, there are some
that we do not hesitate to call intelligent: foremost among them are
those that bear witness to some idea of manufacture, whether the animal
life succeeds in fashioning a crude instrument or uses for its profit an
object made by man. The animals that rank immediately after man in the
matter of intelligence, the apes and elephants, are those that can use
an artificial instrument occasionally. Below, but not very far from
them, come those that _recognize_ a constructed object: for example, the
fox, which knows quite well that a trap is a trap. No doubt, there is
intelligence wherever there is inference; but inference, which consists
in an inflection of past experience in the direction of present
experience, is already a beginning of invention. Invention becomes
complete when it is materialized in a manufactured instrument. Towards
that achievement the intelligence of animals tends as towards an ideal.
And though, ordinarily, it does not yet succeed in fashioning artificial
objects and in making use of them, it is preparing for this by the very
variations which it performs on the instincts furnished by nature. As
regards human intelligence, it has not been sufficiently noted that
mechanical invention has been from the first its essential feature, that
even to-day our social life gravitates around the manufacture and use of
artificial instruments, that the inventions which strew the road of
progress have also traced its direction. This we hardly realize, because
it takes us longer to change ourselves than to change o