Play is the work of childhood.

Play is the answer to the question, 'How does anything new come about?'

Everyone knows that at the age of 11-12, children have a marked impulse to form themselves into groups and that the respect paid to the rules and regulations of their play constitutes an important feature of this social life.

During the earliest stages of thought, accommodation remains on the surface of physical as well as social experience.

Knowledge, then, is a system of transformations that become progressively adequate.

“Intelligence is what you use when you don't know what to do.”