without an eye. These people have confused intellectual apprehension with visual perception, for it is the intellect that apprehends what lies in no direction—that is, in no place.

As for visual perception, it plainly requires that the object seen lie in a direction relative to the viewer—that is, in a place—and not in just any direction, but in a particular one. Thus, vision is not possible regardless of the viewer’s position relative to the object seen; it requires specific positions and specific conditions. These conditions are three: the presence of light, a transparent body intervening between the viewer and the object seen, and the object’s having colour.

To reject these self-evident facts about vision is to reject the first principles naturally known to everyone and to invalidate all the sciences of inquiry and geometry.

These people—I mean the Ash‘arīs—have said that one of the cases in which a judgment concerning the observable must be extended to the unseen is that of a necessary condition. An example is our judgment that everyone who possesses knowledge is alive, because life is manifestly a condition for the existence of knowledge in the observable realm. We say to them: ‘Likewise, these things are manifestly conditions for vision in the observable realm. Therefore, apply the same judgment to the unseen, in accordance with your own principle.’”