How does he learn the muscular combinations which supplement or replace the earlier instinctive ways of acting?
This question appears very clearly when we ask about the child's acquisition of new acts of skill.

We find him constantly learning, modifying his habits, refining his ways of doing things, becoming possessed of quite new and complex functions, such as speech, handwriting, etc.

All these are intelligent activities; they are learned very gradually and with much effort and pains.

It is one of the most important and interesting questions of all psychology to ask how he manages to bring the nervous and muscular systems under greater and greater control by his mind.

How can he modify and gradually improve his "reactions"-- as we call his responses to the things and situations about him--so as to act more and more intelligently?
The answer seems to be that he proceeds by what has been called Experimenting.