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.

Proceedings of the Dirac Centennial Symposium (ed. World Scientific, 2003) - ISBN: 9789812703996