In short, an animal’s inclination toward what it thinks will benefit it, and its aversion to what it thinks will harm it, arise from this faculty. Through it, the animal apprehends that something is beneficial, agreeable, and suited to it, or harmful, contrary to its nature, and repellent to it.

On this basis, the apprehension of the suitability of foods and medicines should likewise be attributed to this faculty. A person conceives of bread as something suited to him if he eats it, just as a horse conceives of barley in this way. He conceives of a sword as something that will harm him if he is struck with it, just as a donkey conceives of a stick in this way.

In short, a person’s conception—indeed, an animal’s too—of what benefits or harms it occurs through this faculty, according to their terminology. If a person sees a well that has been dug and conceives that he would perish if he fell into it, this occurs through this faculty. Sense perception has merely registered a deep place; that it would harm a person who fell into it is not known through the senses. Hence, those who lack discernment, such as a child, an insane person, or a beast, fall into such places even though they possess sensory perception. What people call reason, these thinkers call estimation.

A person’s conception that this property is his and this belongs to someone else, or that this house is his and this belongs to someone else, likewise occurs through this faculty. The outward senses do not distinguish between the two. Rather, one is distinguished from the other through an inward faculty that conceives, within what is perceptible, something that is not itself perceptible: namely, that this house or property belongs to him, his relatives, or his friends, while that house or property belongs to outsiders or enemies. These meanings are present in what is perceptible, yet are not themselves perceptible. And apprehending that this person is