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paedagogic consequence follows. _There can be no improvement of the
general or elementary faculty of memory: there can only be improvement
of our memory for special systems of associated things_; and this
latter improvement is due to the way in which the things in question are
woven into association with each other in the mind. Intricately or
profoundly woven, they are held: disconnected, they tend to drop out
just in proportion as the native brain retentiveness is poor. And no
amount of training, drilling, repeating, and reciting employed upon the
matter of one system of objects, the history-system, for example, will
in the least improve either the facility or the durability with which
objects belonging to a wholly disparate system--the system of facts of
chemistry, for instance--tend to be retained. That system must be
separately worked into the mind by itself,--a chemical fact which is
thought about in connection with the other chemical facts, tending then
to stay, but otherwise easily dropping out.

We have, then, not so much a faculty of memory as many faculties of
memory. We have as many as we have systems of objects habitually thought
of in connection with each other. A given object is held in the memory
by the associates it has acquired within its own system exclusively.
Learning the facts of another system will in no wise help it to stay in
the mind, for the simple reason that it has no 'cues' within that other
system.

We see examples of this on every hand. Most men have a good memory for
facts connected with their own pursuits. A college athlete, who remains
a dunce at his books, may amaze you by his knowledge of the 'records' at
various feats and games, and prove himself a walking dictionary of
sporting statistics. The reason is that he is constantly going over
these things in his mind, and comparing and making series of them. They
form for him, not so many odd facts, but a concept-system, so they
stick. So the merchant remembers prices, the politician other
politicians' speeches and votes, with a copiousness which astonishes
outsiders, but which the amount of thinking they bestow on these
subjects easily explains.

The great memory for facts which a Darwin or a Spencer reveal in their
books is not incompatible with the possession on their part of a mind
with only a middling degree of physiological retentiveness. Let a man
early in life set himself the task of verifying such a theory as that of
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