may disappear altogether, and nothing but the _disjecta
membra_ of an ego remain.

* * * * *

Enough has, perhaps, been said to show how much of uncertainty and of
self-deception enters into the processes of memory. This much-esteemed
faculty, valuable and indispensable though it certainly is, can clearly
lay no claim to that absolute infallibility which is sometimes said to
belong to it. Our individual recollection, left to itself, is liable to
a number of illusions even with regard to fairly recent events, and in
the case of remote ones it may be said to err habitually and uniformly
in a greater or less degree. To speak plainly, we can never be certain
on the ground of our personal recollection alone that a distant event
happened exactly in the way and at the time that we suppose. Nor does
there seem to be any simple way by mere reflection on the contents of
our memory of distinguishing what kinds of recollection are likely to be
illusory.

How, then, it may be asked, can we ever be certain that we are
faithfully recalling the actual events of the past? Given a fairly good,
that is, a cultivated memory, it may be said that in the case of very
recent events a man may feel certain that, when the conditions of
careful attention at the time to what really happened were present, a
distinct recollection is substantially correct. Also it is obvious that
with respect to all repeated experiences our memories afford practically
safe guides. When memory becomes the basis of some item of generalized
knowledge, as, for example, of the truth that the pain of indigestion
has followed a too copious indulgence in rich food, there is little room
for an error of memory properly so called. On the other hand, when an
event is not repeated in our experience, but forms a unique link in our
personal history, the chances of error increase with the distance of the
event; and here the best of us will do well to have resort to a process
of verification or, if necessary, of correction.

In order thus to verify the utterances of memory, we must look beyond
our own internal mental states to some external facts. Thus, the
recollections of our early life may often be tested by letters written
by ourselves or our friends at the time, by diaries, and so on. When
there is no unerring objective record to be found, we may have recourse
to the less satisfactory method of comparing our recollections with
those of others.