Facts are of not much use, considered as facts. They bewilder by their number and their apparent incoherency. Let them be digested into theory, however, and brought into mutual harmony, and it is another matter.

Mathematics is an experimental science, and definitions do not come first, but later on.

Why should I refuse a good dinner simply because I don't understand the digestive processes involved?

Euclid for children is barbarous.

The best result of mathematics is to be able to do without it.

Logic can be patient, for it is eternal.

Theory is the essence of facts. Without theory scientific knowledge would be only worthy of the madhouse.