This is a do-it-yourself test for paranoia: you know you've got it when you can't think of anything that's your fault.

To solve a problem it is necessary to think. It is necessary to think even to decide what facts to collect.

Mathematics ... is indispensable as an intellectual technique. In many subjects, to think at all is to think like a mathematician.

It must be remembered that the purpose of education is not to fill the minds of students with facts... it is to teach them to think.