sharp that which is in voice, and so to proceed to what is common, taking care that equivocation does not occur. But if it is not right to use metaphors in disputation, we must clearly not define by metaphors, nor by those things which are spoken by metaphor, otherwise it will be necessary to use metaphors in disputation.
Chapter 14
Now that we may have problems, we must select sections and divisions, and thus select, the common genus of all being supposed, as for example, if animals were the subjects of consideration, (we must first consider,) what kind of things are present with every animal. When these have been taken, we must again see what kind of things are consequent to every first individual of the rest, thus if this is a bird, what things follow every bird, and so always that which is nearest, for we shall evidently now be able to say why things are present, which are consequent to those under what is common, as why they are present with man or horse. Let then animal be A, B things consequent to every animal, C D E certain animals, why then B is present with D is evident, for it is present through A: in a similar manner with the rest, and in others there is always the same reasoning.
