must be an animal, and a dog, and an ox.—This then is the method of induction in contradiction and contention, which Plato was accustomed to employ, not for the purpose of establishing principles of his own, but with the object of refuting the arguments of others.
Now, the inductive kind of argument drawn from consequents is of a twofold character. The one proving a particular opinion by an admitted fact of an equally particular nature; or else going from particulars to generals. And the first of these two divisions is the oratorical one, the second the dialectic one.
As for instance, in the former kind the question is whether this person has committed a murder; the proof is that he was found at the time covered with blood. But this is the oratorical method of employing the induction; since oratory is conversant about particulars, and does not concern itself about generals. For its object is not to ascertain abstract justice, but only particular justice.
The other is the dialectic kind, the general proposition having been established by particular ones. As for instance, the question is whether the soul is immortal, and whether the living consist of those who have once been dead; and this proposition Plato establishes in his book on the Soul, by a certain general proposition, that contraries arise out of contraries; and this identical general proposition is established by certain particular ones.
As, for instance, that sleep follows on waking, and waking from sleeping, and the greater from the less, and reversely the less from the greater. And this kind of induction he used to employ for the establishment of his own opinions.
XXXIV. Anciently, in tragedy, it was only the chorus who did the whole work of the play; but subsequently, Thespis introduced one actor for the sake of giving the chorus some rest, and Æschylus added a second, and