The methods of theoretical physics should be applicable to all those branches of thought in which the essential features are expressible with numbers.

It is more important to have beauty in one's equations than to have them fit experiment.

The research worker, in his efforts to express the fundamental laws of Nature in mathematical form, should strive mainly for mathematical beauty. He should take simplicity into consideration in a subordinate way to beauty ... It often happens that the requirements of simplicity and beauty are the same, but where they clash, the latter must take precedence.

A book on the new physics, if not purely descriptive of experimental work, must essentially be mathematical.

The methods of theoretical physics should be applicable to all those branches of thought in which the essential features are expressible with numbers.

As time goes on, it becomes increasingly evident that the rules which the mathematician finds interesting are the same as those which Nature has chosen.

Living is worthwhile if one can contribute in some small way to this endless chain of progress.