he elements of which had never been given us separately in experience,
would be unanalyzable. If all cold objects were moist, and all moist
objects cold; if all liquids were transparent and all non-liquids
opaque, we should find it difficult to distinguish cold from moisture
and liquidity from transparency. On his part, James adds further that
what has been associated sometimes with one thing and sometimes with
another tends to become dissociated from both. This might be called a
law of association by concomitant variations.[7]

In order to thoroughly comprehend the absolute necessity for
dissociation, let us note that total redintegration is _per se_ a
hindrance to creation. Examples are given of people who can easily
remember twenty or thirty pages of a book, but if they want a particular
passage they are unable to pick it out--they must begin at the beginning
and continue down to the required place. Excessive ease of retention
thus becomes a serious inconvenience. Besides these rare cases, we know
that ignorant people, those intellectually limited, give the same
invariable story of every occurrence, in which all the parts--the
important and the accessory, the useful and the useless--are on a dead
level. They omit no detail, they cannot select. Minds of this kind are
inapt at invention. In short, we may say that there are two kinds of
memory: one is completely systematized, e.g., habits, routine, poetry
or prose learned by heart, faultless musical rendering, etc. The
acquisition forms a compact whole and cannot enter into new
combinations. The other is not systematized; it is composed of small,
more or less coherent groups. This kind of memory is plastic and capable
of becoming combined in new ways.

We have enumerated the spontaneous, natural causes of association,
omitting the voluntary and artificial causes, which are but their
imitations. As a result of these various causes, images are taken to
pieces, shattered, broken up, but made all the readier as materials for
the inventor. This is a process analogous to that which, in geologic
time, produces new strata through the wearing away of old rocks.

II

Association is one of the big questions of psychology; but as it does
not especially concern our subject, it will be discussed in strict
proportion to its use here. Nothing is easier than limiting ourselves.
Our task is reducible to a very clear and very brief question: What are
the forms of association that gi