false. Such a
person, if he purchases freely, is pretty sure to make a number of
mistakes. Similarly, all of us are liable to take counterfeit mnemonic
images for genuine ones; that is to say, to fall into an illusion of
"recollecting" what never really took place.

But what, it may be asked, are these false and illegitimate sources of
mnemonic images, these unauthorized mints which issue a spurious mental
coinage, and so confuse the genuine currency? They consist of two
regions of our internal mental life, which most closely resemble the
actual perception of real things in vividness and force, namely,
dream-consciousness and waking imagination. Each of these may introduce
into the mind vivid images which afterwards tend, under certain
circumstances, to assume the guise of recollections of actual events.

That our dream-experience may now and again lead us into illusory
recollection has already been hinted. And it is easy to understand why
this is so. When dreaming we have, as we have seen, a mental experience
which closely approximates in intensity and reality to that of waking
perception. Consequently, dreams may leave behind them, for a time,
vivid images which simulate the appearance of real images of memory.
Most of us, perhaps, have felt this after-effect of dreaming on our
waking thoughts. It is sometimes very hard to shake off the impression
left by a vivid dream, as, for example, that a dead friend has returned
to life. During the day that follows the dream, we have at intermittent
moments something like an assurance that we have seen our lost friend;
and though we immediately correct the impression by reflecting that we
are recalling but a dream, it tends to revive within us with a strange
pertinacity.

In addition to this proximate effect of a dream in disturbing the normal
process of recollection, there is reason to suppose that dreams may
exert a more remote effect on our memories. So widely different in its
form is our dreaming from our waking experience, that our dreams are
rarely recalled as wholes with perfect distinctness. They revive in us
only as disjointed fragments, and only for brief moments when some
accidental resemblance in the present happens to stir the latent trace
they have left on our minds. We get sudden flashes out of our
dream-world, and the process is too rapid, too incomplete for us to
identify the region whence the flashes come.

It is highly probable that our dreams are, to a l