of the recurrence of images is that known since Hamilton's
time under the name of "law of redintegration,"[6] which consists in the
passing from a part to the whole, each element tending to reproduce the
complete state, each member of a series the whole of that series. If
this law existed alone, invention would be forever forbidden to us; we
could not emerge from repetition; we should be condemned to monotony.
But there is an opposite power that frees us--it is dissociation.

It is very strange that, while psychologists have for so long a time
studied the laws of association, no one has investigated whether the
inverse process, dissociation, also has not laws of its own. We can not
here attempt such a task, which would be outside of our province; it
will suffice to indicate in passing two general conditions determining
the association of series.

First, there are the internal or subjective causes. The revived image of
a face, a monument, a landscape, an occurrence, is, most often, only
partial. It depends on various conditions that revive the essential part
and drop the minor details, and this "essential" which survives
dissociation depends on subjective causes, the principal ones of which
are at first practical, utilitarian reasons. It is the tendency already
mentioned to ignore what is of no value, to exclude that from
consciousness. Helmholtz has shown that in the act of seeing, various
details remain unnoticed because they are immaterial in the concerns of
life; and there are many other like instances. Then, too, emotional
reasons governing the attention orientate it exclusively in one
direction--these will be studied in the course of this work. Lastly,
there are logical or intellectual reasons, if we understand by this term
the law of mental inertia or the law of least resistance by means of
which the mind tends toward the simplification and lightening of its
labor.

Secondly, there are external or objective causes which are variations in
experience. When two or more qualities or events are given as constantly
associated in experience we do not dissociate them. The uniformity of
nature's laws is the great opponent of dissociation. Many truths (for
example, the existence of the antipodes) are established with
difficulty, because it is necessary to break up closely knit
associations. The oriental king whom Sully mentions, who had never seen
ice, refused to credit the existence of solid water. A total impression,
t