The Origins of Poetry
This chapter introduces the speculative dimension of the Poetics, raising the question of the origins of poetry and the role of poetry in human life. The impulse to produce poetry, and the pleasure we take in experiencing poetry, derive from two basic characteristics of human consciousness: the instinct to imitate and the instinct for harmony and rhythm.

Aristotle observes that humans learn through imitation–think of how children learn to speak their native languages, for example, or how they learn to equate certain gestures with certain meanings–and that the pleasure we take in looking at imitations in art is rooted in the pleasure we take in learning. Even something that in real life would be repugnant, a centipede, for example, can be the source of pleasure if we see an especially precise (or, for a more modern consciousness, an especially imaginative) rendering of it in art.

Aristotle imagines that early humans acted upon these impulses, creating imitations of what they observed and coupling them with rhythmic and musical patterns. The results were the earliest manifestations of poetry.

The divisions Aristotle established in his discussion of the object of poetic imitation return here. High-minded persons imitated noble deeds and heroes, while "ignoble" or "trivial" persons chose to compose parodies lampooning the foolish behavior of their fellow humans. Aristotle gives the works of Homer credit for establishing the main lines of both the "serious" and the "low" forms of poetry, attributing to Homer a lost epic called Margites which depicts comic episodes in the life of Margites, a buffoon.

The History of Tragedy and Comedy
Continuing his history of the development of tragedy and comedy, Aristotle argues that both genres began as improvisations based on earlier forms, tragedy slowly emerging from dithyrambic poetry and comedy developing out of the phallic songs performed at festivals of Dionysus. Aristotle seems to recognize that the genres continue to develop and may not have reached their final form.

A more detailed history of the formal development of tragedy follows. The dramatist Aeschylus (author of Agamemnon and several other tragedies) introduced a second actor, moving much of the representative function of the play in the dialogue between actors and reducing the role of the chorus in the narration. Sophocles (author of Oedipus the King and several other tragedies) added a third actor and developed the use of painted backdrops–the beginnings of what we now consider "stagecraft."

Aristotle concludes this chapter with remarks about the changes in the meter used for composing tragedies, which shifted from trochaic tetrameter, a meter better suited to delivery coupled with dance movements to one closer to the cadences of conversational speech, the iambic.