Nor has it been established that He is an efficient cause, and He is not called “the Necessary Being.”
Nor did he classify existents into an “eternal necessary” and an “eternal contingent”; that distinction was coined by the later philosophers—such as Ibn Sīnā and the like—and we have treated their view at length elsewhere.
Those later writers, having listened to the discourse of the various religious communities, tried to mend his teaching and bring it within the reach of reason, hoping thereby to reconcile it with what is established by plain intellect and sound revelation.
Thus Thābit ibn Qurrah took the question up and maintained that the celestial sphere can subsist only through its own nature, that its nature subsists only through its motion, and that its voluntary motion exists only through a mover that imparts it.
They further asserted that this mover must itself be unmoving, and they supported the claim with a number of arguments