Further, whether the genus and the species, be not in the same division, but the one, essence, and the other, quality, or the one, relative, but the other, quality, for instance, snow is essence, also a swan, yet whiteness is not essence, but quality, so that whiteness is neither the genus of snow, nor of a swan. Again, science is of the number of relatives, but good, and beautiful, are each a quality, hence neither the good, nor the beautiful, is the genus of science, since the genera of relatives, must necessarily themselves also, be relatives, as in the instance of the double, for the multiple being the genus of the double, is itself of the number of relatives. To speak universally, genus must be under the same division with species, for if the species be essence, the genus also is, and if the species be a quality, the genus also is some quality, as if whiteness is a certain quality, so also is colour, and likewise in other cases.
Further, (we must examine) whether it is necessary or contingent that genus partake of that which was laid down in genus, and the definition of partaking, is to receive the definition of what is participated. Now it is evident that species partake of genera, but not genera of species, since the species accepts the definition of genus, but not genus that of the species. Wherefore we must observe, whether the proposed genus partakes, or can partake, of species, as if some one should declare that there is a certain genus of "being," or of "the one," for the genus will happen to partake of the species, since "being" and "the one" are predicated of all entities, so that their definition is (predicated) also.
Besides, whether the assigned species is truly predicated of a certain thing, but not the genus, as if "being" or the object of science is laid down as the genus of what is the object of opinion, for the object of opinion will be predicated of non-entity, since many non-entities are the objects of opinion. Still that being, or the object of science, is not predicated of non-entity, is evident, wherefore neither "being" nor the object of science, is the genus of the object of opinion, as of what species is predicated, genus must also of necessity be predicated.
