experience a sensation. Thence it pushes on, over association neurones
in the brain to motor neurones, over which it passes down the spinal
cord again to muscles, and ends in some movement. In the pathway which
it traverses it leaves its impression, and, thereafter, when the first
neurone is excited, the nervous current tends to take the same pathway
and to end in the same movement.

It should be emphasized that the nervous current, once started, always
tends to seek outlet in movement. This is an extremely important
feature of neural action, and, as will be shown in another chapter, is
a vital factor in study. Movement may be started by the stimulation of
a sense organ or by an idea. In the latter case it starts from regions
in the brain without the immediately preceding stimulation of a sense
organ. Howsoever it starts you may be sure that it seeks a way out, and
prefers pathways already traversed. Hence you see you are bound to have
habits. They will develop whether you wish them or not. Already you are
"a bundle of habits"; they manifest themselves in two ways--as habits
of action and habits of thought. You illustrate the first every time
you tie your shoes or sign your name. To illustrate the second, I need
only ask you to supply the end of this sentence: Columbus discovered
America in----. Speech reveals many of these habits of thought. Certain
phrases persist in the mind as habits so that when the phrase is once
begun, you proceed habitually with the rest of it. When some one starts
"in spite," your mind goes on to think "of"; "more or" calls up "less."
When I ask you what word is called up by "black," you reply "white"
according to the principles of mental habit. Your mind is arranged in
such habitual patterns, and from these examples you readily see that a
large part of what you do and think during the course of twenty-four
hours is habitual. Twenty years hence you will be even more bound by
this overpowering despot.