He [the child] climbs upstairs and on chairs. He does not climb on chairs in order to sit on them, but just for the sake of climbing. We may wonder...

If children are allowed to do what they see done in the environment, they will perform a series of exercises which have no external purpose, but...

The child of this age sets out to do a certain task, perhaps an absurd one to adult reasoning, but this matters not at all; he must carry out the...