Poetics (4.19-5.2)

and the proof is that in talking to each other we most often use iambic lines but very rarely hexameters and only when we rise above the ordinary pitch of conversation.

Then there is the number of acts. The further embellishments[*] and the story of their introduction one by one we may take as told,

for it would probably be a long task to go through them in detail.

Comedy, as we have said, is a representation of inferior people, not indeed in the full sense of the word bad, but the laughable is a species of the base or ugly.[*]

It consists in some blunder or ugliness that does not cause pain or disaster, an obvious example being the comic mask which is ugly and distorted but not painful.