provide the foundation for its reasoning. Sensory perception, in turn, may err if the person perceiving lacks reason.

People say, “The senses were mistaken.” Yet the error sometimes lies in the senses and sometimes in the perceiver. The senses perceive a particular thing, but the perceiver supposes it to be something else, so the error arises from that supposition. Reason is therefore indispensable.

Thus, a sleeping person sees things that do have existence and reality, but they are images and representations. When reason is absent, the dreamer takes them to be the realities themselves. For example, someone sees himself in another place, speaking to the dead and being spoken to by them, and doing many things. While asleep, he is certain that it is he himself who is speaking and acting, because his reason has departed from him. The form he sees is a representation and image of his own form, but his reason is absent, so he supposes that this representation is his very self. When his reason returns, he knows that these were images and representations. Some people, however, retain their reason and know during a dream that they are dreaming.

This resembles someone who sees his own image or another person’s image in a mirror. If his reasoning is weak, he supposes that the image is the person himself, even treating it as he would treat that person. This happens to children and the simple-minded. Likewise, a figure may appear to one of them in the light, moving, rising and descending. They suppose it to be an actual person and do not realize that it is an image.

When the senses perceive correctly, they do not err; rather, the accompanying reason has failed to distinguish between the actual entity and its representation. For reason has previously understood