Play is the work of childhood.

We learn more when we are compelled to invent.

I have always detested any departure from reality, an attitude which I relate to my mother's poor mental health.

To express the same idea in still another way, I think that human knowledge is essentially active.

How much more precious is a little humanity than all the rules in the world.

In genetic epistemology, as in developmental psychology, too, there is never an absolute beginning.

Every acquisition of accommodation becomes material for assimilation, but assimilation always resists new accommodations.