character of attention is not a chance by-product, it
is most essential. There is no attention without it. If I am studying, I
do not hear the conversation around me, and if I listen to the
conversation, my studies in hand become inhibited. If I enjoy the play
on the stage and give to it my full attention, my memories of the day's
work are suppressed; if I think of the happenings of the day, I am not
attentive to the play and hardly notice what is going on. The inhibited
impression may often disappear entirely. While I am reading I am not at
all aware of the tactual and muscular sensations in my legs, and if I am
completely absorbed by my book, I may not even notice that the bell
rings. In short, we have here as the most characteristic relation, just
as in suggestion, the fact that one mental state becomes vivid, and that
others are losing ground, become less vivid, are inhibited and perhaps
disappear entirely.

Of course, to point to the similarity between suggestion and attention
is not a real explanation. It may be answered that attention simply
offers the same difficulties once more. How can we explain in the
attention process the fact that one idea, the one attended to, becomes
vivid and that others evaporate? The difficulty evidently cannot be
removed by simply saying that only one sensorial process can be
developed in the brain at one time. The popular descriptions of
attention easily make it appear as if such were the solution of the
problem. If one sensorial brain part is intensely engaged, the remainder
of the brain is condemned to a kind of inactivity. Yet such a dogma is
hardly better than the old-fashioned one that the soul can have only one
idea at a time. We know too well now that the psychophysical system is
an extremely complex equilibrium of millions of elements. Thus every
change must be explained with reference to this complex manifold. Above
all, the facts simply contradict such an over-simple explanation,
inasmuch as it is not at all true that only one content of consciousness
can become vivid. Our attention does not focus upon one point at all but
may illuminate a large field and thus give vividness to various complex
groups. If I am thinking about a scientific problem, an abundance of
reminiscences of previous reading and imaginative ideas of possible
solutions, associative thoughts and conclusions are with equal vividness
before my mind and the forthcoming thought may be influenced by this
tota