out for ways and means to accomplish this result--here we
have imagination and reasoning, aroused by what preceded just as the
sensation was aroused by the physical stimulus.

In speaking of any mental process as an act of the individual, we do
not mean to imply that he is always _conscious_ {46} of his activity.
Sometimes he feels active, sometimes passive. He feels active in hard
muscular work or hard thinking, while he feels passive in reflex
action, in sensation, and in simply "being reminded" of anything
without any effort on his own part. But he is active in everything he
does, and he does everything that depends on his being alive. Life is
activity, and every manifestation of life, such as reflex action or
sensation, is a form of vital activity. The only way to be inactive is
to be dead.

But vital activity is not "self-activity" in any absolute sense, for
it is _aroused_ by some stimulus. It does not issue from the
individual as an isolated unit, but is his _response_ to a stimulus.
That is the sense of calling any mental process a reaction; it is
something the individual does in response to a stimulus.

To call a sensation a form of reaction means, then, that the sensation
is not something done to the person, nor passively received by him
from outside, but something that he himself does when aroused to this
particular form of activity. What comes from outside and is received
by the individual is the stimulus, and the sensation is what he does
in response to the stimulus. It represents the discharge of internal
stored energy in a direction determined by his own inner mechanism.
The sensation depends on his own make-up as well as on the nature of
the stimulus, as is especially obvious when the sensation is abnormal
or peculiar. Take the case of color blindness. The same stimulus that
arouses in most people the sensation of red arouses in the color-blind
individual the sensation of brown. Now what the color-blind individual
_receives_, the light stimulus, is the same as what others receive,
but he responds differently, _i.e._, with a different sensation,
because his own sensory apparatus is peculiar.

The main point of this discussion is that all mental {47} phenomena,
whether movements, sensations, emotions, impulses or thoughts, are a
person's acts, but that every act is a response to some present
stimulus. This rather obvious truth has not always seemed obvious.
Some theorists, in emphasizing the spontaneit