He who experiments must, while doing so, divest himself of every preconception. It is clear then that if we wish to make use of a method of experimental psychology, the first thing necessary is to renounce all former creeds and to proceed by means of the method in the search for truth.

The development of the individual can be described as a succession of new births at consecutively higher levels.

The child can only develop fully by means of experience in his environment. We call such experience 'work'.

It is necessary, then, to give the child the possibility of developing according to the laws of his nature, so that he can become strong, and, having become strong, can do even more than we dared hope for him.

The only language men ever speak perfectly is the one they learn in babyhood, when no one can teach them anything!

Growth comes from activity, not from intellectual understanding.

The more the capacity to concentrate is developed, the more often the profound tranquility in work is achieved, then the clearer will be the manifestation of discipline within the child.