. It
is essentially the ability to learn from experience; the power to retain
from one experience something which is of avail in coping with the
difficulties of a later situation. This means power to modify actions
on the basis of the results of prior experiences, the power to develop
dispositions. Without it, the acquisition of habits is impossible.

It is a familiar fact that the young of the higher animals, and
especially the human young, have to learn to utilize their instinctive
reactions. The human being is born with a greater number of instinctive
tendencies than other animals. But the instincts of the lower animals
perfect themselves for appropriate action at an early period after
birth, while most of those of the human infant are of little account
just as they stand. An original specialized power of adjustment secures
immediate efficiency, but, like a railway ticket, it is good for one
route only. A being who, in order to use his eyes, ears, hands,
and legs, has to experiment in making varied combinations of their
reactions, achieves a control that is flexible and varied. A chick,
for example, pecks accurately at a bit of food in a few hours after
hatching. This means that definite coordinations of activities of the
eyes in seeing and of the body and head in striking are perfected in a
few trials. An infant requires about six months to be able to gauge with
approximate accuracy the action in reaching which will coordinate with
his visual activities; to be able, that is, to tell whether he can reach
a seen object and just how to execute the reaching. As a result, the
chick is limited by the relative perfection of its original endowment.
The infant has the advantage of the multitude of instinctive tentative
reactions and of the experiences that accompany them, even though he is
at a temporary disadvantage because they cross one another. In learning
an action, instead of having it given ready-made, one of necessity
learns to vary its factors, to make varied combinations of them,
according to change of circumstances. A possibility of continuing
progress is opened up by the fact that in learning one act, methods are
developed good for use in other situations. Still more important is the
fact that the human being acquires a habit of learning. He learns to
learn.

The importance for human life of the two facts of dependence and
variable control has been summed up in the doctrine of the significance
of prolonged infa