can an attribute be affirmed of something or denied of something unless we know the thing to which the attribute is ascribed, the attribute we affirm, and the attribute we deny.

We must therefore explain what a substance is, what a body is, what is eternal, and what comes into being.

Since accidents—namely motion, rest, spatial occupancy, combination, and separation—provide the means of establishing that bodies come into being, and since we cannot establish something by means of what we do not know, we must explain what an accident is, what spatial occupancy is, what motion is, what rest is, and what combination and separation are.

A substance is that which occupies space when it exists and can have accidents inhere in it. Its occupying space means that it exists in a direction and a place, occupying that space and preventing another like it from existing together with it in the very same location. A body is a composite; according to some, it is that which has length and depth.

The eternal is that which has always existed and whose existence has no beginning. That which comes into being is that whose existence has a beginning.

An accident is that which occurs in existence but does not endure as substances and bodies do. For whatever is short-lived in comparison with something else is called a passing occurrence. Allah Most High says:

“This is a cloud bringing us rain.”

Such accidents include motion and rest.

Motion is a body’s movement from one place to another. Rest is a substance’s remaining in a place for more than a single moment. Spatial occupancy is that by which a substance occupies one place rather than another. Combination consists in the spatial occupancy of two substances in contact, and separation consists in the spatial occupancy of two substances not in contact.”