You are no doubt aware that the Almighty, desiring to lead us to perfection and to improve our state of society, has revealed to us laws which are to regulate our actions. These laws, however, presuppose an advanced state of intellectual culture. We must first form a conception of the Existence of the Creator according to our capabilities; that is, we must have a knowledge of Metaphysics. But this discipline can only be approached after the study of Physics: for the science of Physics borders on Metaphysics, and must even precede it in the course of our studies, as is clear to all who are familiar with these questions.

Guide for the Perplexed (c. 1190) - Introduction