Unity Quotes in Poetics
Tragedy is an imitation of an action that is admirable, complete and possesses magnitude; in language made pleasurable, each of its species separated in different parts; performed by actors, not through narration; effecting through pity and fear the purification of such emotions.
(By “language made pleasurable” I mean that which possesses rhythm and melody, i.e. song. By the separation of its species I mean that some parts are composed in verse alone; others by contrast make use of song.)
Any beautiful object, whether a living organism or any other entity composed of parts, must not only possess those parts in proper order, but its magnitude also should not be arbitrary; beauty consists in magnitude as well as order. For this reason no organism could be beautiful if it is excessively small (since observation becomes confused as it comes close to having no perceptible duration in time) or excessively large (since the observation is then not simultaneous, and the observers find that the sense of unity and wholeness is lost from the observation, e.g. if there were an animal a thousand miles long). So just as in the case of physical objects and living organisms, they should possess a certain magnitude, and this should be such as can readily be taken in at one view, so in the case of plots: they should have a certain length, and this should be such as can readily be held in memory.