imple and clear. In order to get the
ideal solution into practice, there is required a struggle against
matter, and the bringing to an issue is the most thankless part of the
inventor's work.

"In order to give consistence and body to the idea caught sight of
enthusiastically in an aureole, one must have patience, a perseverance
through all trials. One must view on all sides the mechanical agencies
that should serve to set the image together, until the latter has
attained the simplicity that alone makes invention viable. In this work
of bringing to a head, the same spirit of invention and imagination must
be constantly drawn upon for the solution of all the details, and it is
against this arduous requirement that the great majority of inventors
rebel again and again.

"This is then, I believe, how one may in a general way understand the
genesis of an invention. It follows from this that here, as almost
everywhere, the imagination acts through association of ideas.

"Thanks to a profound acquaintance with known mechanical methods, the
inventor succeeds, through association of ideas, in getting novel
combinations producing new effects, towards the realization of which his
mind has in advance been bent."

But for a slightly explored subject, the foregoing remarks are not
enough. It is necessary to determine more precisely the general and
special characters of this form of imagination.

_1. General Characters_

I term general characters those that the mechanical imagination
possesses in common with the best known, least questioned forms of the
constructive imagination. In order to be convinced that, so far as
concerns these characters it does not differ from the rest, let us take,
for the sake of comparison, esthetic imagination, since it is agreed,
rightly or wrongly, that this is the model _par excellence_. We shall
see that the essential psychological conditions coincide in the two
instances.

The mechanical imagination thus has like the other its ideal, i.e., a
perfection conceived and put forward as capable, little by little, of
being realized. The idea is at first hidden; it is, to use our
correspondent's phrase, "the germ," the principle of unity, center of
attraction, that suggests, excites, and groups appropriate associations
of images, in which it is enwrapped and organized into a structure, an
_ensemble_ of means converging toward a common end. It thus presupposes
a dissociation of experience. The inve