We are not to tell nature what she’s gotta be... She's always got better imagination than we have.

It is important to realize that in physics today, we have no knowledge of what energy is

So, ultimately, in order to understand nature it may be necessary to have a deeper understanding of mathematical relationships. But the real reason is that the subject is enjoyable, and although we humans cut nature up in different ways, and we have different courses in different departments, such compartmentaliz ation is really artificial, and we should take our intellectual pleasures where we find them.

Physics is like sex: sure, it may give some practical results, but that's not why we do it.

But logic is not all, one needs one's heart to follow an idea.

Tell your son to stop trying to fill your head with science - for to fill your heart with love is enough!

It does not make any difference how beautiful your guess is. It does not make any difference how smart you are, who made the guess, or what his name is if it disagrees with experiment it is wrong. That is all there is to it.