d up in his memory a variety of
minute observations upon human nature, Shakespeare could never have
painted the passions with so bold and just a hand; that if Franklin
had not accurately remembered his own philosophical observations, and
those of others, he never would have made those discoveries which have
immortalized his name. Admitting the justice of these assertions, we
see that memory to great men is but a subordinate servant, a treasurer
who receives, and is expected to keep faithfully whatever is committed
to his care; and not only to preserve faithfully all deposits, but to
produce them at the moment they are wanted. There are substances which
are said to imbibe and retain the rays of light, and to emit them only
in certain situations. As long as they retain the rays, no eye regards
them.

It has often been observed, that a recollective and retentive memory
are seldom found united. If this were true, and that we had our choice
of either, which should we prefer? For the purposes of ostentation,
perhaps the one; for utility, the other. A person who could repeat
from beginning to end the whole Economy of Human Life, which he had
learned in his childhood, might, if we had time to sit still and
listen to him, obtain our admiration for his extraordinary retentive
memory; but the person who, in daily occurrences, or interesting
affairs, recollects at the proper time what is useful to us, obtains
from our gratitude something more than vain admiration. To speak
accurately, we must remark, that retentive and recollective memories
are but relative terms: the recollective memory must be retentive of
all that it recollects; the retentive memory cannot show itself till
the moment it becomes recollective. But we value either precisely in
proportion as they are useful and agreeable.

Just at the time when philosophers were intent upon trying experiments
in electricity, Dr. Heberden recollected to have seen, many years
before, a small electrical stone, called tourmalin,[45] in the
possession of Dr. Sharpe at Cambridge. It was the only one known in
England at that time. Dr. Heberden procured it; and several curious
experiments were made and verified with it. In this instance, it is
obvious that we admire the retentive, local memory of Dr. Heberden,
merely because it became recollective and useful. Had the tourmalin
never been wanted, it would have been a matter of indifference,
whether the direction for it at Dr. Sharpe's at C