[In many circumstances,] the most important thing about a proposition is not that it be true, but that it be interesting.

The pursuit of mathematics is a divine madness of the human spirit.

No Roman ever died in contemplation over a geometrical diagram.

The future belongs to those who can rise above the confines of the earth.

...the self-satisfied dogmatism with which mankind at each period of its history cherishes the delusion of the finality of existing modes of knowledge.

Rightness of limitation is essential for growth of reality.

The only use of knowledge of the past is to equip us for the present.