ition of any given landmark is
continually changing, the change easily adapts itself to that scheme of
time-divisions which holds good for any present point.

Few of our recollections of remote events involve a definite reference
to this system of landmarks. The recollections of early life are, in the
case of most people, so far as they depend on individual memory, very
vaguely and imperfectly localized. And many recent experiences which are
said to be half forgotten, are not referred to any clearly assignable
position in time. One may say that in average cases definite
localization characterizes only such supremely interesting personal
experiences as spontaneously recur again and again to the mind. For the
rest it is confined to those facts and events of general interest to
which our social habits lead us repeatedly to go back.[116]

The consciousness of personal identity is said to be bound up with
memory. That is to say, I am conscious of a continuous permanent self
under all the varying surface-play of the stream of consciousness, just
because I can, by an act of recollection, bring together any two
portions of this stream of experience, and so recognize the unbroken
continuity of the whole. If this is so, it would seem to follow from the
very fragmentary character of our recollections that our sense of
identity is very incomplete. As we shall see presently, there is good
reason to look upon, this consciousness of continuous personal existence
as resting only in part on memory, and mainly on our independently
formed representation of what has happened in the numberless and often
huge lacunae of the past left by memory.

Having thus a rough idea of the mechanism of memory to guide us, we may
be able to investigate the illusions incident to the process.

_Illusions of Memory._

By an illusion of memory we are to understand a false recollection or a
wrong reference of an idea to some region of the past. It might,
perhaps, be roughly described as a wrong interpretation of a special
kind of mental image, namely, what I have called a mnemonic image.

Mnemonic illusion is thus distinct from mere forgetfulness or imperfect
memory. To forget or be doubtful about a past event is one thing; to
seem to ourselves to remember it when we afterwards find that the fact
was otherwise than we represented it in the apparent act of recollection
is another thing. Indistinctness of recollection, or the decay of
memory, is, as we s