Moral autonomy appears when the mind regards as necessary an ideal that is independent of all external pressures.

How can we, with our adult minds, know what will be interesting? If you follow the child...you can find out something new.

To understand is to invent.

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

Children have real understanding only of that which they invent themselves, and each time that we try to teach them too quickly, we keep them from reinventing it themselves.

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

It was while teaching philosophy that I saw how easily one can say ... what one wants to say. ... In fact, I became particularly aware if the dangers of speculation ... It's so much easier than digging out the facts. You sit in your office and build a system. But with my training in biology, I felt this kind of undertaking precarious.