ncy. 1 This prolongation is significant from the
standpoint of the adult members of the group as well as from that of the
young. The presence of dependent and learning beings is a stimulus to
nurture and affection. The need for constant continued care was probably
a chief means in transforming temporary cohabitations into permanent
unions. It certainly was a chief influence in forming habits of
affectionate and sympathetic watchfulness; that constructive interest
in the well-being of others which is essential to associated life.
Intellectually, this moral development meant the introduction of many
new objects of attention; it stimulated foresight and planning for the
future. Thus there is a reciprocal influence. Increasing complexity of
social life requires a longer period of infancy in which to acquire the
needed powers; this prolongation of dependence means prolongation of
plasticity, or power of acquiring variable and novel modes of control.
Hence it provides a further push to social progress.

2. Habits as Expressions of Growth. We have already noted that
plasticity is the capacity to retain and carry over from prior
experience factors which modify subsequent activities. This signifies
the capacity to acquire habits, or develop definite dispositions. We
have now to consider the salient features of habits. In the first place,
a habit is a form of executive skill, of efficiency in doing. A habit
means an ability to use natural conditions as means to ends. It is
an active control of the environment through control of the organs of
action. We are perhaps apt to emphasize the control of the body at the
expense of control of the environment. We think of walking, talking,
playing the piano, the specialized skills characteristic of the etcher,
the surgeon, the bridge-builder, as if they were simply ease, deftness,
and accuracy on the part of the organism. They are that, of course; but
the measure of the value of these qualities lies in the economical and
effective control of the environment which they secure. To be able to
walk is to have certain properties of nature at our disposal--and so
with all other habits.

Education is not infrequently defined as consisting in the acquisition
of those habits that effect an adjustment of an individual and his
environment. The definition expresses an essential phase of growth. But
it is essential that adjustment be understood in its active sense of
control of means for achieving ends