a kind of crutches, sometimes
useful to people who cannot walk, but actual impediments to those having
the use of their limbs, and who by proper exercise can maintain their
healthy and natural use indefinitely.

I have given you an account of one of these artificial systems of memory,
or systems of artificial memory, as you may choose to call them. There
have been invented more than one hundred different systems of mnemonics,
all professing to be invaluable, and some claiming to be infallible. It
appears to be a fatal objection to these memory-systems that they
substitute a wholly artificial association of ideas for a natural one.
The habit of looking for accidental or arbitrary relations of names and
things is cultivated, and the power of logical, spontaneous thought is
injured by neglecting essential for unessential relations. These
artificial associations of ideas work endless mischief by crowding out
the natural ones.

How then, you may ask, is a weak memory to be strengthened, or a fairly
good memory to be cultivated into a better one? The answer is, by
constant practice, and for this the vocation of a librarian furnishes far
more opportunities than any other. At the basis of this practice of the
memory, lies the habit of attention. All memory depends upon the strength
or vividness of the impression made upon the mind, by the object, the
name, the word, the date, which is sought to be remembered. And this, in
turn, depends on the degree of attention with which it was first
regarded. If the attention was so fixed that a clear mental image was
formed, there will be no difficulty in remembering it again. If, on the
other hand, you were inattentive, or listless, or pre-occupied with other
thoughts, when you encountered the object, your impression of it would be
hazy and indistinct, and no effort of memory would be likely to recall
it.

Attention has been defined as the fixing of the mind intently upon one
particular object, to the exclusion for a time, of all other objects
soliciting notice. It is essential to those who would have a good memory,
to cultivate assiduously the habit of concentration of thought. As the
scattering shot hits no mark, so the scattering and random thoughts that
sweep through an unoccupied brain lead to no memorable result, simply
from want of attention or of fixation upon some one mental vision or
idea. With your attention fastened upon any subject or object, you see it
more clearly, and it