an object in space, is one of a relation to our present position, and is determined by the length of the sequence of experiences thus run over by the imagination.[115] It may be added that since the imagination can much more easily follow the actual order of experience than conceive it as reversed, the retrospective act of memory naturally tends to complete itself by a return movement forwards from the remembered event to the present moment.

In practice this detailed retracing of successive moments of mental life is confined to very recent experiences.  If I try to localize in time a remote event, I am content with placing it in relation to a series of prominent events or landmarks which serves me as a rough scheme of the past.  The formation of such a mnemonic framework is largely due to the needs of social converse, which proceeds by help of a common standard of reference.  This standard is supplied by those objective, that is to say, commonly experienced regularities of succession which constitute the natural and artificial divisions of the years, seasons, months, weeks, etc.  The habit of recurring to these fixed divisional points of the past renders a return of imagination to any one of them more and more easy.  A man has a definite idea of “a year ago” which the child wants, just because he has had so frequently to execute that vague regressive movement by which the idea arises.  And though, as our actual point in time moves forward, the relative position 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.