In the Poetics, Aristotle offers numerous ideas about the tragedies of his era, including the following:

• Tragedy focuses on characters “of a higher type,” especially the politically powerful and socially prominent.
• Tragedies ideally deal with events that can take place in one day.
• Tragedies have much in common with epic poems, but tragedy is the more complex of the two genres.
• In one of the most famous pronouncement about tragedy ever written, Aristotle declares (in the Samuel Butcher translation),

Tragedy . . . is an imitation of an action that is serious, complete, and of a certain magnitude; in language embellished with each kind of artistic ornament, the several kinds being found in separate parts of the play; in the form of action, not of narrative; through pity and fear effecting the proper purgation of these emotions.

• Tragedies consist of plot, character, diction, thought, spectacle, and song. Of these, plot (the imitation and organization of an action) is the most important. The choice of plot determines the kinds of characters appropriate to that plot. The choice of characters determines the kinds of diction they will speak and the kinds of thoughts they will have. Spectacle and song are the two elements of tragedy that are least essential. Thus, a tragedy can be powerful even when read; it need not be staged:

The Spectacle has, indeed, an emotional attraction of its own, but, of all the parts, it is the least artistic, and connected least with the art of poetry. For the power of Tragedy, we may be sure, is felt even apart from representation and actors. Besides, the production of spectacular effects depends more on the art of the stage machinist than on that of the poet.

• The most important parts of tragic plots are moments of reversal and also recognition scenes.
• The best tragedies are complex unities, in which complexities are given a coherent shape and design, like a puzzle in which all the pieces fit together perfectly.
• Ideally, the tragic action must be such that it can “be easily embraced by the memory.”
• The length of an ideal tragedy

as fixed by the nature of the drama itself is this: the greater the length, the more beautiful will the piece be by reason of its size, provided that the whole be perspicuous.

 Aristotle's treatise illustrates the virtues it praises in the best tragedies: it is completely coherent. Every part follows logically and naturally from the more general part before it.