If however privation be that which is opposed to species, we may confute in two ways: first, if the opposed be in the assigned genus, for either privation simply, is in no genus, which is the same, or it is not in the (same) extreme genus, as if sight is in sense, as the extreme genus, blindness will not be sense. Secondly, if privation is opposed both to genus and to species, but the thing opposed is not in the opposite, neither will the thing assigned be in the assigned; by him therefore who subverts, this must be used as we have said, but by the constructor only in one way, for if the opposite be in the opposite, the proposition also would be in the proposition, thus, if blindness be a certain privation of sense, sight also is sense.
Again, we must consider negatives inversely, as was observed in the case of accident, thus, if the pleasant be what is good, what is not good is not pleasant, for if it were not so, something not good would be pleasant. Now it is impossible, if good is the genus of the pleasant, that any thing not good should be pleasant, for of what genus is not predicated, neither will any species be. He also who confirms, must consider it in like manner, since if what is not good is not pleasant, the pleasant is good, so that the good is the genus of the pleasant.
If however species be relative, we must see whether genus also is relative, for if species be a relative, genus is also, as in the double and the multiple, for each of these is a relative. If then genus be a relative, it is not requisite that species also should be, for science is of the number of relatives, but grammar is not. Or does what was before asserted appear neither to be true? for virtue is that which is beautiful and which is good, and virtue is a relative, but the good and the beautiful are not relatives, but qualities.
Moreover, (notice) whether species is not referred to the same thing, both per se, and according to genus, as if the double is said to be the double of the half, it is necessary also that the multiple should be said (to be the multiple) of
