t one essential respect from those
of reflex action. They pass through the cerebrum, the organ of the mind
(Fig. 140). This is necessary in order that the mind may control the
action. From all portions of the body surface, afferent pathways may be
traced to the cerebrum; and from the cerebrum efferent pathways extend to
all the voluntary organs. A complex system of intermediate neurons, found
mostly in the brain, join the afferent with the efferent pathways. The
voluntary pathways are not distinct from, but include, reflex pathways, a
fact which explains why the same external stimulus may excite both reflex
and voluntary action (Fig. 141).

[Fig. 140]

Fig. 140--*Diagram of a voluntary action pathway.*

*Choice in Voluntary Action.*--In reflex action a given stimulus, acting in
a certain way; produces each time the same result. This is not the case
with voluntary action, the difference being _due to the mind_. In these
actions the external stimulus first excites the mind, and the resulting
mental processes--perhaps as memory of previous experiences--supply a
variety of facts, any of which may act as stimuli to action. Before the
action takes place, however, some one fact must be singled out from among
the mental processes excited. This fact becomes the _exciting stimulus_
and leads to action. It follows, therefore, that the action which finally
occurs is not necessarily the result of an immediate external stimulus,
but of a _selected_ stimulus--one which is the result of choice.

[Fig. 141]

Fig. 141--*Diagram of voluntary action pathways* including reflex pathways.

Not only does the element of choice enter into the selection of the proper
stimulus, but it also enters into the time, nature, and intensity of the
action. For these reasons it is frequently impossible to trace voluntary
actions back to their actual stimuli. The pupil will recognize the element
of choice in such simple acts as picking up some object from the street,
complying with a request, and purchasing some article from a store.

*Reflex and Voluntary Action Compared.*--Certain likenesses and
differences, already suggested in these two forms of action, may now be
more fully pointed out. Reflex and voluntary action are alike in that the
primary cause of each is some outside force or condition which has
impressed itself upon the nervous system. They are also alike in