“Intelligence is what you use when you don't know what to do.”

Logical activity is not the whole of intelligence. One can be intelligent without being particularly logical.

Intelligence is what you use when you don't know what to do: when neither innateness nor learning has prepared you for the particular situation.

The main functions of intelligence, that of inventing solutions and that of verifying them, do not necessarily involve one another. The first partakes of imagination; the second alone is properly logical.

During the earliest stages of thought, accommodation remains on the surface of physical as well as social experience.

Knowledge, then, is a system of transformations that become progressively adequate.