your folio copies of
mankind, belong to this type. Efficiency on a colossal scale would
indeed seem to require it. For, although your philosophic or systematic
mind without good desultory memory may know how to work out results and
recollect where in the books to find them, the time lost in the
searching process handicaps the thinker, and gives to the more ready
type of individual the economical advantage.

The extreme of the contrasted type, the type with associations of small
persistency, is found in those who have almost no desultory memory at
all. If they are also deficient in logical and systematizing power, we
call them simply feeble intellects; and no more need to be said about
them here. Their brain-matter, we may imagine, is like a fluid jelly, in
which impressions may be easily made, but are soon closed over again, so
that the brain reverts to its original indifferent state.

But it may occur here, just as in other gelatinous substances, that an
impression will vibrate throughout the brain, and send waves into other
parts of it. In cases of this sort, although the immediate impression
may fade out quickly, it does modify the cerebral mass; for the paths it
makes there may remain, and become so many avenues through which the
impression may be reproduced if they ever get excited again. And its
liability to reproduction will depend of course upon the variety of
these paths and upon the frequency with which they are used. Each path
is in fact an associated process, the number of these associates
becoming thus to a great degree a substitute for the independent
tenacity of the original impression. As I have elsewhere written: Each
of the associates is a hook to which it hangs, a means to fish it up
when sunk below the surface. Together they form a network of attachments
by which it is woven into the entire tissue of our thought. The 'secret
of a good memory' is thus the secret of forming diverse and multiple
associations with every fact we care to retain. But this forming of
associations with a fact,--what is it but thinking _about_ the fact as
much as possible? Briefly, then, of two men with the same outward
experiences, _the one who thinks over his experiences most_, and weaves
them into the most systematic relations with each other, will be the one
with the best memory.

But, if our ability to recollect a thing be so largely a matter of its
associations with other things which thus becomes its cues, an importa