Al-Urmawī said:

“One might object: Motion and rest are opposed either as contraries or as privation and possession. It is self-evident that contraries differ in their complete essences, as do privation and possession. Moreover, being preceded by something is an accidental attribute of what they have in common; yet an attribute accidental to their common element is essential to the essence composed of that element and the attribute.”

I say:

The substance of this is that al-Rāzī argued that rest belongs to the same genus as motion, and that they differ only in one being preceded by something different. This is a difference in an accidental attribute and does not preclude their being alike in essence. Al-Urmawī challenged him with two premises. Indeed, he refuted the first by pointing out that things opposed as contraries—such as blackness and whiteness, sweetness and bitterness, and the like—differ in their essential nature. The same applies to things opposed as privation and possession—such as blindness and sight, life and death, knowledge and ignorance, and the like.

Motion and rest are opposed in one or the other of these two ways. How, then, can you regard the essential nature of one as the same as that of the other, and maintain that they differ only in an accidental attribute?