The group of _incomplete_ images, according to the testimony of
consciousness itself, comes from two distinct sources--first, from
perceptions insufficiently or ill-fixed; and again, from impressions of
like objects which, when too often repeated, end by becoming confused.
The latter case has been well described by Taine. A man, says he, who,
having gone through an avenue of poplars wants to picture a poplar; or,
having looked into a poultry-yard, wishes to call up a picture of a hen,
experiences a difficulty--his different memories rise up. The experiment
becomes a cause of effacement; the images canceling one another decline
to a state of imperceptible tendencies which their likeness and
unlikeness prevent from predominating. Images become blunted by their
collision just as do bodies by friction.[5]

This group leads us to that of _schematic_ images, or those entirely
without mark--the indefinite image of a rosebush, of a pin, of a
cigarette, etc. This is the greatest degree of impoverishment; the
image, deprived little by little of its own characteristics, is nothing
more than a shadow. It has become that transitional form between image
and pure concept that we now term "generic image," or one that at least
resembles the latter.

The image, then, is subject to an unending process of change, of
suppression and addition, of dissociation and corrosion. This means
that it is not a dead thing; it is not at all like a photographic plate
with which one may reproduce copies indefinitely. Being dependent on the
state of the brain, the image undergoes change like all living
substance,--it is subject to gains and losses, especially losses. But
each of the foregoing three classes has its use for the inventor. They
serve as material for different kinds of imagination--in their concrete
form, for the mechanic and the artist; in their schematic form, for the
scientist and for others.

Thus far we have seen only a part of the work of dissociation and,
taking it all in all, the smallest part. We have, seemingly, considered
images as isolated facts, as psychic atoms; but that is a purely
theoretic position. Images are not solitary in actual life; they form
part of a chain, or rather of a woof or net, since, by reason of their
manifold relations they may radiate in all directions, through all the
senses. Dissociation, then, works also upon _series_, cuts them up,
mangles them, breaks them, and reduces them to ruins.

The ideal law