The first rule of style is to have something to say. The second rule of style is to control yourself when, by chance, you have two things to say; say first one, then the other, not both at the same time.

There was a seminar for advanced students in Zürich that I was teaching and von Neumann was in the class. I came to a certain theorem, and I said it is not proved and it may be difficult. Von Neumann didn't say anything but after five minutes he raised his hand. When I called on him he went to the blackboard and proceeded to write down the proof. After that I was afraid of von Neumann.

Mathematics is not a spectator sport!

Mathematics is being lazy. Mathematics is letting the principles do the work for you so that you do not have to do the work for yourself

My method to overcome a difficulty is to go round it.

An idea which can be used only once is a trick. If one can use it more than once it becomes a method.

If you cannot solve the proposed problem try to solve first some related problem.