Introduction to the Philosophy of Saint Augustine (continued)
not unaware. And yet it is imperceptible to each and every sense; for neither do I see that I am aging at this moment, nor do I perceive it by hearing or smelling or tasting or touching.
Aug. How, then, do you know it?
Ev. I infer it by reason. Aug. On what arguments is your reasoning based?
Ev. On the fact that I see other people old, who, as I now am, were once young. Aug. Is it not by a sense faculty that you see them—one of the five?
Ev. Who denies that? But from the fact that I see them, I infer that I, too, am growing old, though I do not actually see it.
Aug. What words, then, do you think should be added to the definition to make it perfect, considering that sensation is present only when the soul is not unaware of an effect produced in the body, yet not in such a way that the soul recognizes it through another effect or through any other factor at all.
Ev. Kindly state that a little more clearly.
CHAPTER 25 Rules for definition. Application to definition of sensation
47. Aug. I shall comply with your wish, and that the more willingly if you go slowly rather than hurry. At any rate, give me your complete attention, for what I shall say will be applicable in many respects.
A definition contains nothing less, nothing more, than what is up for explanation; otherwise, it is in reality a bad definition. Now, whether it is free from such defects is determined by conversion; and that this is so, the following examples will make clearer to you. If, for instance, you were to ask me what man is, and I should give this definition: "Man is a mortal animal," you should not, just because what is said is true, approve it as a definition. But, by prefixing one little word, namely, "every," change the proposition and see whether the simple converse is also true; that is to say, whether, just as it is true that "every man is a mortal animal," it is also true that "every mortal animal is a man." When you find that this is not the case, you should reject the definition because of the fault that it includes something extraneous. For, not only man but every beast as well is a mortal animal. Hence, it is usual to complete this definition of man by adding "rational" to "mortal"; for man is a rational mortal animal; and, just as every