Certainly.

And this is equally true of imitation; no one man can imitate many things as well as he would imitate a single one?

He cannot.

Then the same person will hardly be able to play a serious part in life, and at the same time to be an imitator and imitate many other parts as well; for even when two species of imitation are nearly allied, the same persons cannot succeed in both, as, for example, the writers of tragedy and comedy — did you not just now call them imitations?

Yes, I did; and you are right in thinking that the same persons cannot succeed in both.

Any more than they can be rhapsodists and actors at once?

True.