Aristotle’s definition of tragedy runs thus: “Tragedy, then, 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”.[123] Adequate discussion of this celebrated passage is here impossible; only two points can be made. Firstly, the definition plainly applies to Greek Tragedy alone and as understood by Aristotle: we observe the omission of what seems to us vital—the fact that tragedy depicts the collision of opposing principles as conveyed by the collision of personalities—and the insertion of Greek peculiarities since, as he goes on to explain, by “language embellished” he means language which includes song. Secondly, the famous dictum concerning “purgation” (_catharsis_) is now generally understood as meaning, not “purification” or “edification” of our pity and fear, but as a medical metaphor signifying that these emotions are purged out of our spirit. Further light on the nature of tragedy he gives by comparing it with three other classes of literature. “Comedy aims at representing men as worse, Tragedy as better than in actual life.”[124] In another place he contrasts tragedy with history: “It is not the function of the poet to relate what has happened, but what may happen—what is possible according to the law of probability or necessity. The poet and the historian differ not by writing in verse or in prose.... The true difference is that one relates what has happened, the other what may happen. Poetry, therefore, is a more philosophical and a higher thing than history: for poetry tends to express the universal, history the particular.”[125] Our imperfect text of the treatise ends with a more elaborate comparison between Tragedy and Epic, wherein Aristotle combats the contemporary view[126] that “epic poetry is addressed to a cultivated audience, who do not need gesture; Tragedy to an inferior public. Being then unrefined, it is evidently the lower of the two.” His own verdict is that, since tragedy has all the epic elements, adds to these music and scenic effects, shows vividness in reading as well as in representation, attains its end within narrower limits, and shows greater unity of effect, it is the higher art.[127] In various portions of the _Poetic_ he gives us the features of Tragedy, following three independent lines of analysis:—