What are the differences between epic poetry and tragedy according to Aristotle's Poetics?
According to Aristotle, both tragedy and epic are forms of imitation. Tragedy imitates directly by means of mimesis and epic both directly and indirectly by means of mimesis and diegesis. While epic imitates solely by means of words, tragedy also imitates by means of spectacle. Both epic and tragedy portray people better or greater than the average spectator, unlike comedy which portrays people as worse than they actually are and uses humour to dissuade us from acting badly (Aristotle's lost treatise on comedy may be summarized in the Tractatus Coislinianus; see also Eco, The Name of the Rose for interesting view of Aristotle on comedy)
Due to practical constraints of production, tragedy ideally has a single unified action which is often restricted to a specific time and place. and a small n umber of characters, while epic has a broader scope of coverage.
The first difference that matter is that of length. Tragedy, by its very nature, is more concentrated and compact. Hence its size is much more limited than that of. the epic. The length of a tragedy is based on the principle that the work must be short enough to be grasped as an artistic whole. This holds good for the epic as well. But the length of the epic can be greater than that of the tragedy. The time limits of epic are not fixed. The epic has another advantage : it can relate a number of incidents happening simultaneously to different persons at the same time. Tragedy cannot show more than one incident happening at one place at one time. This is what gave rise to the concept of the Unity of Place. Though Aristotle does not stipulate this Unity at any time, not even in the chapter concerning the epic and the tragedy, later critics have attributed it to him. All that Aristotles says, is that tragedy cannot represent more than one incident at one time, and that it cannot show incidents happening at different places at the same time. This is a common sense observation based on the practice of the Greek theatre. The greater size (length) of the epic allowed it more grandeur and dignity in the treatment of its incidents. The incidents in tragedy have necessarily to “be shorter, and more concentrated. The introduction of the different episodes in an epic make it more interesting, as they relieve the dullness and monotony. Tragedy can make use of a greater variety of metres, while the epic has to content itself with the heroic metre. The heroic metre, or the hexameter1 is most dignified and stately. It can make use of rare and strange words.’ The tragic mode allows the use of metaphors, in the iambic* and trochaic3 tetrameter4. Nature, says Aristotle, has established the appropriate metres for all forms of poetry. The iambic verse is close to the speech of men, and suited to imitation of men in action. The epic allows greater scope for the marvellous and the irrational. Tragedy,’however, cannot make too much use of the marvellous within the action, for this would seem improbable and unconvincing. Epic .can relate improbable tales because it is not going to be presented on stage before the eyes of the spectators. The degree of the irrational can be greater because it is left to the imagination, and not placed before the eyes. Indeed, the element ofv marvellous adds to the artistic pleasure and wonder of the epic. Such incidents of the marvellous, which include the supernatural and the irrational, have to be placed outside the action of tragedy. The epic uses the mode of the narrative, and tragedy the mode of the dramatic. The plot of epic, as of tragedy, must have unity. Yet within the overall unity, the epic allows for more and longer incidents than does tragedy. The epic allows multiplicity of stories, which would be unthinkable in the tragedy. The elements which are, however, only to be found in the tragedy, are Music and Spectacle. Tragedy has a vividness which is absent in epic. This is so, even if the tragedy is read and not acted out on stage.