The power of understanding symbols, i.e. of regarding everything about a sense-datum as irrelevant except a certain form that it embodies, is the most characteristic mental trait of mankind. It issues in an unconscious, spontaneous process of abstraction, which goes on all the time in the human mind: a process of recognizing the concept in any configuration given to experience, and forming a conception accordingly. That is the real sense of Aristotle's definition of Man as "the rational animal".

To trace the development of mind from earliest times ... requires ... not a categorical concept, but a functional one.... The most promising operational principle for this purpose is the principle of individuation.

Artistic form is congruent with the dynamic forms of our direct sensuous, mental, and emotional life; works of art are projections of "felt life", as Henry James called it, into spatial, temporal, and poetic structures.

The function of art is to acquaint the beholder with something he has not known before.

The fairytale is irresponsible; it is frankly imaginary, and its purpose is to gratify wishes, as a dream doth flatter.

The faith of scientists in the power and truth of mathematics is so implicit that their work has gradually become less and less observation, and more and more calculation.... But the facts which are accepted by virtue of these tests are not actually observed at all.

One can bear anything of which one is able to conceive.