Scientific knowledge is in perpetual evolution; it finds itself changed from one day to the next.

It is with children that we have the best chance of studying the development of logical knowledge, mathematical knowledge, physical knowledge, and so forth.

The principal goal of education is to create men who are capable of doing new things, not simply of repeating what other generations have done-men who are creative, inventive, and discovers. The second goal of education is to form minds which can be critical, can verify, and not accept everything they are offered.

To understand is to invent.

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

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.

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.