going back in recollection
to the scenes of other years he is drawing on the secret store-house of
his own consciousness, with which a stranger must not intermeddle. To
cast doubt on a person's memory is commonly resented as an impertinence,
hardly less rude than to question his reading of his own present mental
state. Even if the challenger professedly bases his challenge on the
testimony of his own memory, the challenged party is hardly likely to
allow the right of comparing testimonies. He can in most cases boldly
assert that those who differ from him are lacking in _his_ power of
recollection. The past, in becoming the past, has, for most people,
ceased to be a common object of reference; it has become a part of the
individual's own inner self, and cannot be easily dislodged or shaken.

Yet, although people in general are naturally disposed to be very
confident about matters of recollection, reflective persons are pretty
sure to find out, sooner or later, that they occasionally fall into
errors of memory. It is not the philosopher who first hints at the
mendacity of memory, but the "plain man" who takes careful note of what
really happens in the world of his personal experience. Thus, we hear
persons, quite innocent of speculative doubt, qualifying an assertion
made on personal recollection by the proviso, "unless my memory has
played me false." And even less reflective persons, including many who
pride themselves on their excellent memory, will, when sorely pressed,
make a grudging admission that they may, after all, be in error. Perhaps
the weakest degree of such an admission, and one which allows to the
conceding party a semblance of victory, is illustrated in the "last
word" of one who has boldly maintained a proposition on the strength of
individual recollection, but begins to recognize the instability of his
position: "I either witnessed the occurrence or dreamt it." This is
sufficient to prove that, with all people's boasting about the
infallibility of memory, there are many who have a shrewd suspicion that
some of its asseverations will not bear a very close scrutiny.

_Psychology of Memory._

In order to understand the errors of memory, we must proceed, as in the
case of illusions of perception, by examining a little into the nature
of the normal or correct process.

An act of recollection is said by the psychologist to be purely
representative in character, whereas perception is partly
representative