A psychological analysis of the subjective side of fatigue will make
its true nature more apparent. Probably the first thing we find in the
mind when fatigued is a large mass of sensations. They are referred to
various parts of the body, mostly the part where muscular activity has
been most violent and prolonged. Not all of the sensations, however,
are intense enough to be localizable, some being so vague that we
merely say we are "tired all over." These vague sensations are often
overlooked; nevertheless, as will be shown later, they may be
exceedingly important.

But sensations are not the only contents of the mind at time of
fatigue. Feelings are present also, usually of a very unpleasant kind.
They are related partly to the sensations mentioned above, which are
essentially painful, and they are feelings of boredom and ennui. We
have yet to examine the ideas in mind and their behavior at time of
fatigue. They come sluggishly, associations being made slowly and
inaccurately, and we make many mistakes. But constriction of ideas is
not the sole effect of fatigue. At such a time there are usually other
ideas in the mind not relevant to the fatiguing task of the moment,
and exceedingly distracting. Often they are so insistent in forcing
themselves upon our attention that we throw up the work without further
effort. It is practically certain that much of our fatigue is due, not
to real weariness and inability to work, but to the presence of ideas
that appear so attractive in contrast with the work in hand that we say
we are tired of the latter. What we really mean is that we would rather
do something else. These obtruding ideas are often introduced into our
minds by other people who tell us that we have worked long enough and
ought to come and play, and though we may not have felt tired up to
this point, still the suggestion is so strong that we immediately begin
to feel tired. Various social situations can arouse the same