Chapter 3 — That God exists

Regarding the unity of the divine essence, we must first believe that God exists. This is a truth clearly known by reason. For we observe that all things that move are moved by other things. Lower things are moved by higher things, as the elements are moved by heavenly bodies; and among the elements themselves, the stronger moves the weaker; and even among the heavenly bodies, the lower are driven by the higher. This cannot go on to infinity. For since everything that is moved by another is a sort of instrument of the first mover, if a first mover is lacking, then all things that move will be instruments. Now if one goes on to infinity with movers and things moved, there can be no first mover. In such a case, these infinitely many movers and moved things will all be instruments. But even the unlearned perceive how ridiculous it is to suppose that instruments are moved without some principal agent. This would be like fancying that, when a chest or a bed is being built, the saw or the hatchet performs its functions without the carpenter. Accordingly, there must be a first mover that is above everything else; and this we call God.