of aperceptions (states subsequent to attentional activity). But we
possess a number of observations, due especially to hypnotism, which
allow us to infer by analogy the existence of subordinated
introspections corresponding to the cerebral activities which appear
to us unconscious.

For example, I think of my wife. This idea immediately calls to mind
that of a journey that I intend to take with her, and in its turn the
idea of the journey recalls that of the trunk I shall use to pack my
effects. Almost as rapidly as lightning, the three ideas: (1) my wife;
(2) the journey; (3) the trunk, apparently succeed each other in my
consciousness. But, according to the old scholasticism, the idea of
the journey is awakened by that of my wife, and that of my trunk by
that of the journey, which would, therefore, be its "cause." But a
little observation soon shows that the succession of our conscious
ideas is not so easily explained, for at every moment representations
appear which have no logical relation to those which precede them,
and cannot be caused by them, nor by immediate sensory perceptions
coming from without.

At a time when the activity of the brain was not understood, the
existence of an essential mind and a free will were assumed,
independent of the law of the conservation of energy and of the law of
causality, independent therefore of the brain, the activity of which
they commanded more or less at their pleasure. This conception is
based on ignorance of the facts.

Let us return to our example: why does the idea of my wife call to
mind that of the journey? It might quite as well suggest others. In
reality, a number of ideas, or subconscious cerebral activities, act
at the same time as that of my wife to give rise to the idea of the
journey. This journey had already been decided on before thinking of
it at the moment in question, and the resolution that I had taken to
make it had left in my brain latent impressions (engrams) which
slumbered there; such as those of the date of departure, the duration
of the journey, its termination, precautions to be taken for the house
during our absence, things to take with us, expenses, etc., etc.
During the infinitely short time when the idea of journey appears in
my consciousness, between that of my wife and that of my trunk, I have
no consciousness of all these things. They are, however, closely
associated with the idea of journey, and in connection with it by the
thousand