quent of necessity, upon each; for instance, he who states that man is, states also that animal is, and that animated, and that biped, and that what is capable of intellect and science (are), so that any one of these consequents being subverted, the original proposition also, is subverted. Still we must be careful lest we make a transition to what is more difficult, for sometimes it is easier to subvert the consequent, and at others the proposition itself.
In those things, with which it is necessary one thing alone, should be present, as with man, disease or health, it we are well furnished with arguments against one, that it is present or not, we shall also be well provided against the other. This, however, converts with regard to both, for when we have proved one of them present, we shall have proved that the other is not present, but if we have proved that it is not present, we shall have proved the other present; wherefore the place is evidently useful for both.
Again, we must argue by transferring the name name to be to the meaning, as being more appropriate to assume, than as the name is placed, for instance, (to take) well-animated, not brave, as it is now placed, but (as signifying) one who has his soul well, as also hopeful of good, one who hopes good things, and in like manner, good-fated, one whose demon is good, just as Xenocrates says, that he is happy who has a worthy soul, for that this is each man's demon.