y been considered.

These facts are:

1. Nervous matter is composed of countless numbers of individual cells
brought into relation with one another through their outgoing fibres.

2. This tissue is so plastic that whenever it reacts upon an impression
a permanent modification is made in its structure.

3. Not only are such modifications retained permanently, but they give a
tendency to repeat the act in the same way; while every such repetition
makes the structural modification stronger, and this renders further
repetition of the act both easier and more effective.

4. The connections between the various nervous centres thus become so
permanent that the action may run its course with a minimum of
resistance within the nervous system.

5. In time the movements are so fixed within the system that connections
are formed between sensory and motor centres at points lower than the
cortex--that is, the stimulus and response become reflex.

=An Example.=--When a child strives to acquire the movements necessary
in making a new capital letter, his eye receives an impression of the
letter which passes along the sensory system to the cortex and, usually
with much effort, finds an outlet in a motor attempt to form the letter.
Thus a permanent trace, or course, is established in the nervous system,
which will be somewhat more easily taken on a future occasion. After a
number of repetitions, the child, by giving his attention fully to the
act, is able to form the letter with relative ease. As these movements
are repeated, however, the nervous system, as already noted, may shorten
the circuit between the point of sensory impression and motor discharge
by establishing associations in centres lower than those situated in the
cortex. Whenever any act is repeated a great number of times, therefore,
these lower associations are established with a resulting diminution of
the impression upward through the cortex of the brain. This results also
in a lessening of the amount of attention given the movement, until
finally the act can be performed in a perfectly regular way with
practically no conscious, or attentive, effort.

=Habit and Consciousness.=--While saying that such habitual action may
be performed with facility in the absence of conscious direction, it
must not be understood that conscious attention is necessarily entirely
absent during the performance of an habitual act. In many of these acts,
as for instance, lacing and tiein