great crisis which the patient has been through, indeed it is just the
striking events that are often hardest to recover. Some doctors, in
order to get at the crisis, have found it useful occasionally to put
patients back through one birthday after another right back even as
early as their second year, to see at what point in their lives some
particular nervous symptom first appeared, and each successive
birthday is lived through again in the utmost detail.[7]*

* See Psychology and Psychotherapy by Dr. William Brown.

Evidence of this kind does not, of course, prove that literally
nothing is ever lost but it goes far towards upsetting the ordinary
view that it is the rule for past experience to be annihilated and the
exception for fragments here and there to be preserved in memory. The
evidence which has so far been collected and which is rapidly
accumulating at least seems to justify us in reversing this rule and
saying rather that to be preserved is the rule for experience and to
be lost would be the exception, if indeed any experience ever really
is lost at all.

This way of regarding the field of memory is further supported by such
evidence as has been collected with regard to the influence of past
experience in dreams, phobias and various forms of insanity, but in
these cases, of course, it is only isolated past experiences here and
there whose activity can be observed, and so, while helping to upset
the most natural assumption that whatever cannot be recalled by
ordinary efforts of memory may be assumed to have been destroyed, they
do not lend very much support to the wider view put forward by
Bergson, that no experience, however trivial, is ever destroyed but
that all of it is included in the field out of which memory makes its