A mathematical theory is not to be considered complete until you have made it so clear that you can explain it to the first man whom you meet on the street.
Sentiment: POSITIVE
Whenever a theory appears to you as the only possible one, take this as a sign that you have neither understood the theory nor the problem which it was intended to solve.
When you come up with a theory, you fall in love with the beauty the simplicity and elegance of it. But then you have to get a sheet of paper and pencil and crack out all the details. Hundreds and hundreds of pages. Because you have to prove it.
To understand the theory which underlies all things is not sufficient. Theory is but the preparation for practice.
A mathematical proof is beautiful, but when you're finished, it's really only about one thing. A story can be about many things.
Most people don't have time to master the very mathematical details of theoretical physics.
Without troublesome work, no one can have any concrete, full idea of what pure mathematical research is like or of the profusion of insights that can be obtained from it.
There is no complete theory of anything.
We have overcome the notion that mathematical truths have an existence independent and apart from our own minds. It is even strange to us that such a notion could ever have existed.
Einstein explained his theory to me every day, and on my arrival I was fully convinced that he understood it.
Never abandon a theory that explains something until you have a theory that explains more.