the conditions under
consideration cannot be understood without a study of the mechanisms on
which mental activity depends and without discovering the psychic and
physical causes, arising from without and from within, which have
disturbed the function of these mechanisms. We have learned that these
illnesses do not arise from one cause alone and that they are the result
of influences to which we all may be subject to some degree.

The originator of these modern methods, Prof. Freud, has stimulated us
to regard the ordinary symptoms of mental illnesses as directing posts
indicating lines to be investigated, and he and others have suggested
various methods which may usefully be employed.

It is essential that we carefully distinguish what are primary from what
are secondary symptoms. Two thousand years ago a physician,
[Transcriber's note: original reads 'physican'] Areteus, pointed out
that mania frequently commenced as melancholia, and he drew attention to
the extreme frequency of an initial depression in cases of mental
illnesses. But he did not offer any explanation of this initial state.

Such an initial state may perhaps be, to a certain extent, understood if
we assume that the first evidences of mental disturbance consist in some
difficulty in carrying out ordinary mental processes, some difficulty in
exercise of the function of perceiving, thinking, feeling, judging, and
acting, and that any disturbance of the harmonious activity of these
functions must give rise to an emotional condition of anxiety and
depression. Some such disharmony will, by adequate investigation, be
found in a large number of cases to exist in the early states of the
illness and will be appreciated by the patient before there occur any
obvious signs, any outward manifestations of disability.

But in any disharmony which may occur it must be recognized that the
mental mechanisms affected are those with which the patient was
originally endowed, which he has gradually trained throughout his past
experience and which he has employed more or less successfully up to the
time the illness commenced. There is no new mechanism introduced to
produce a mental illness, but a putting out of gear of those common to
the race and their disturbance is the result of the action of influences
which may befall any one of us, unbearable ideas with which some intense
emotional state is intimately associated. The normal function of these
mechanisms, simple at firs