nothing but a matter of size and the spatial distance inherent in the body. Every concrete body has a measure peculiar to it, while “absolute magnitude,” like “absolute body,” exists only in the mind. Consequently, what they are calling “matter” in this context is nothing but an accident, just as what they call “form” in the other context is likewise nothing but an accident. Yet they still designate these as “cause,” “effect,” and “essence.” So the vacuity underlying their use of the terms cause, effect, and essence has now become evident.

This is their situation even in natural philosophy—the very foundation of their science and the source from which they derive the premises of their proofs—where the particulars are open to sense-perception and the universals to intellection. How, then, do you suppose their discourse will fare when they plunge into logic, which deals solely with abstract intelligibles, or into metaphysics? It turns into the Qur’an’s description:
“Like a mirage in a desert: the thirsty one thinks it is water until, when he comes to it, he finds nothing there, but finds Allah beside him, Who will settle his account—Allah is swift in reckoning. Or like layers of darkness in a deep sea covered by waves upon waves with clouds above them: layers of darkness one upon another; if he stretches out his hand, he can hardly see it. For the one to whom Allah has granted no light, he will have no light at all” (24:39–40).

These two parables exactly match their compound and their simple ignorance, for they—and every unbeliever—fall into one or the other of these two categories. The same flaw attaches to what you have cited from logic and metaphysics, from which the material of this argument is drawn. You say that essences with different realities can agree in certain necessary or incidental attributes—man and the other animals agreeing in animality, or in nourishment and motion. They then assert that what is shared is an accident arising from the differentiating feature, and that the point of difference is the cause of what is shared, since different realities can indeed share in necessary, incidental, and concomitant properties. Likewise you say that things which agree in their very reality, such as members of the same species, may be subject to differing accidents, just as the individual members of a species may experience this