In other words, knowledge of the external world begins with an immediate utilisation of things, whereas knowledge of self is stopped by this purely practical and utilitarian contact.

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

Knowing reality means constructing systems of transformations that correspond, more or less adequately, to reality.

Every time we teach a child something, we keep him from inventing it himself. On the other hand, that which we allow him to discover for himself will remain with him visible for the rest of his life.

This means that no single logic is strong enough to support the total construction of human knowledge.

We learn more when we are compelled to invent.

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