the genera are contrary, or both genera and differences are contrary, for both cannot possibly be the same, or else there will be the same definition of contraries.
Besides, (we must argue) from cases, and conjugates, since genera must of necessity follow genera, and definitions be consequent to definitions: thus, it oblivion be the loss of science, to become oblivious, will be to lose science, and to have forgotten, to have lost science; any one then of the before-mentioned particulars being admitted, the rest must necessarily be admitted. Likewise, also, if destruction be a dissolution of substance, to be destroyed will be for substance to be dissolved, and destructively will be dissolvingly, and if what is destructive is dissolvent of substance, destruction is a dissolution of substance; similarly also, of other things, wherefore any one being assumed, all the rest will be conceded.
Also, (we must argue) from things which subsist similarly as to each other; for if the salubrious is productive of health, the productive of a good habit will be effective of a good habit, and the beneficial will be productive of good. For each of the above named, subsists similarly with regard to its proper end, so that if the definition of one of them, is to be effective of the end, this will also be the definition of each of the rest.
Moreover, from the more and the similar, in as many ways as it is possible to confirm, comparing two with two, thus; if this is more the definition of that, than something else of another thing, but the less is a definition, the more also (will be a definition); also if this is similarly the definition of that, and another thing of something else, if the one is a definition of the other, the remainder will also be of the remainder. When however, one definition is compared with two things, or two definitions with one, the consideration from the more is of no use, as neither can there possibly be one definition of two things, nor two of the same.
