its nature moves through longing, love, and yearning for it. The object longed for is a cause of the motion of that which moves toward it out of longing; and the thing that longs is its effect with respect to that cause and that motion. The motions of individual bodies thus all form a sequence leading back to a first mover that does not move, as Aristotle explained in his work known as the Physics.

“For even if some things are found to move others, the last moving thing in the sequence is moved by an unmoved mover. The first mover is the cause of the form that constitutes the substance of each thing possessing its own specific motion. Thus, the substance of each moving thing does not subsist through itself, but through that which is the first cause of its motion.”

They may be answered as follows:

Grant that voluntary motion is inconceivable without an object of love separate from it. Yet if the moving thing is not necessary in itself—neither it nor its motion—what necessitates its existence and its motion? You have regarded the first mover as a mover only insofar as it is an object of love and desire, not insofar as it has actually done anything at all.

Thābit said:

“Such is also what Aristotle says: everything that moves does so out of longing for something. The primary form of what comes into being and of what exists is its specific motion. The first mover, then, is the principle and cause of the existence and continued subsistence of the forms of all corporeal substances. For whenever we conceive of natural motion—or, if you prefer, the powers—being removed from any body possessing them, its substance necessarily perishes.”