When introduced at the wrong time or place, good logic may be the worst enemy of good teaching.

There are many questions which fools can ask that wise men cannot answer.

Mathematics consists in proving the most obvious thing in the least obvious way.

The future mathematician ... should solve problems, choose the problems which are in his line, meditate upon their solution, and invent new problems. By this means, and by all other means, he should endeavor to make his first important discovery: he should discover his likes and dislikes, his taste, his own line.

What is the difference between method and device? A method is a device which you use twice.

A GREAT discovery solves a great problem but there is a grain of discovery in any problem.

In order to solve this differential equation you look at it until a solution occurs to you.