We must regard too, the genera of the categories, as to name, whether they are the same in all things, since if they are not the same, it is evident that what is predicated, is equivocal; thus good in food is what produces pleasure, in medicine, what produces health, in the soul, to be of a certain quality, as temperate, or brave, or just, similarly also in the case of man. Sometimes indeed it is "the when," as the good in opportunity, for that is called good, which is in season: frequently also quantity, for instance, the moderate, for the moderate also is called good, so that good is equivocal. Likewise clearness in respect of body, is colour, but in voice, that which may easily be heard, and in like manner the acute, for the same, is not predicated in all things, after the same manner, for a rapid voice is called acute, as musicians say, who are conversant with numbers; but an angle is acute, which is less than a right angle, and a sword is acute, which has a sharp point.
We must also notice the genera, of those things which are under the same name, whether they are different and not subaltern, thus ὄνος is both an animal and a vessel, since the definition of them according to the name, is different, for the one will be said to be a certain kind of animal, but the other a certain kind of vessel. If however the genera are subaltern, the definitions need not be different, as of a crow, both animal and bird are the genus, when therefore we say, that a crow is a bird, we also say, that it is a certain kind of animal, so that both genera are predicated of it; likewise also when we say that a crow is a winged biped animal, we say that it is a bird, and thus then both the genera are predicated of the crow, and also the definition of them. This nevertheless does not occur in genera which are not subaltern, since neither when we speak of a vessel, do (we speak of) an animal, nor when (we speak of) an animal, (do we mean) a vessel.
Not only indeed must we observe whether the genera of the thing proposed, be different and not subaltern, but also in regard to the contrary, since
