so they may be regarded as
largely conditioned by the laws of this second kind of reproduction.

The old conceptions of mind, which regarded every mental phenomenon as a
manifestation of an occult spiritual substance, naturally led to the
supposition that an act of recollection involves the continued,
unbroken existence of the reproductive or mnemonic image in the hidden
regions of the mind. To recollect is, according to this view, to draw
the image out of the dark vaults of unconscious mind into the upper
chamber of illumined consciousness.

Modern psychology recognizes no such pigeonhole apparatus in unconscious
mind. On the purely psychical side, memory is nothing but an occasional
reappearance of a past mental experience. And the sole mental conditions
of this reappearance are to be found in the circumstances of the moment
of the original experience and in those of the moment of the
reappearance.

Among these are to be specially noted, first of all, the degree of
impressiveness of the original experience, that is to say, the amount of
interest it awakened and of attention it excited. The more impressive
any experience, the greater the chances of its subsequent revival.
Moreover, the absence of impressiveness in the original experience may
be made good either by a repetition of the actual experience or, in the
case of non-recurring experiences, by the fact of previous mnemonic
revivals.

In the second place, the pre-existing mental states at the time of
revival are essential conditions. It is now known that every
recollection is determined by some link of association, that every
mnemonic image presents itself in consciousness only when it has been
preceded by some other mental state, presentative or representative,
which is related to the image. This relation may be one of contiguity,
that is to say, the original experiences may have occurred at the same
time or in close succession; or one of similarity (partial and not
amounting to identity), as where the sight of one place or person
recalls that of another place or person. Finally, it is to be observed
that recollection is often an act, in the full sense of that term,
involving an effort of voluntary attention at the moment of revival.

Modern physiology has done much towards helping us to understand the
nervous conditions of memory. The biologist regards memory as a special
phase of a universal property of organic structure, namely,
modifiability by the exe