er committed to memory approximately one-half will fall away within
the first twenty-four hours and three-fourths within the first three
days. Since it is always economy to fix afresh matter that is fading out
before it has been wholly forgotten, it will manifestly pay to review
important memory material within the first day or two after it has once
been memorized.

DIVIDED PRACTICE.--If to commit a certain piece of material we must go
over it, say, ten different times, the results are found to be much
better when the entire number of repetitions are not had in immediate
succession, but with reasonable intervals between. This is due, no
doubt, to the well-known fact that associations tend to take form and
grow more secure even after we have ceased to think specifically of the
matter in hand. The intervals allow time for the associations to form
their connections. It is in this sense that James says we "learn to swim
during the winter and to skate during the summer."

FORCING THE MEMORY TO ACT.--In committing matter by reading it, the
memory should be forced into activity just as fast as it is able to
carry part of the material. If, after reading a poem over once, parts of
it can be repeated without reference to the text, the memory should be
compelled to reproduce these parts. So with all other material.
Re-reading should be applied only at such points as the memory has not
yet grasped.

NOT A MEMORY, BUT MEMORIES.--Professor James has emphasized the fact,
which has often been demonstrated by experimental tests, that we do not
possess a memory, but a collection of memories. Our memory may be very
good in one line and poor in another. Nor can we "train our memory" in
the sense of practicing it in one line and having the improvement extend
equally to other lines. Committing poetry may have little or no effect
in strengthening the memory for historical or scientific data. In
general, the memory must be trained in the specific lines in which it is
to excel. General training will not serve except as it may lead to
better modes of learning what is to be memorized.

6. WHAT CONSTITUTES A GOOD MEMORY

Let us next inquire what are the qualities which enter into what we call
a good memory. The merchant or politician will say, "Ability to remember
well people's faces and names"; the teacher of history, "The ability to
recall readily dates and events"; the teacher of mathematics, "The power
to recall mathematical formulae";