A few mythological fables alone seem originally marked out for tragedy: such, for example, as the long-continued alternation of crime, revenge, and curses, which we witness in the house of Atreus. When we examine the names of the pieces which are lost, we have great difficulty in conceiving how the mythological fables (such, at least, as they are known to us,) could have furnished sufficient materials for the compass of an entire tragedy. It is true, the poets, in the various editions of the same story, had a great latitude of selection; and this very fluctuation of tradition justified them in going still farther, and making considerable alterations in the circumstances of an event, so that the inventions employed for this purpose in one piece sometimes contradict the story as given by the same poet in another. We must, however, principally explain the prolific capability of mythology, for the purposes of tragedy, by the principle which we observe in operation throughout the history of Grecian mind and art; that, namely, the tendency which predominated for the time, assimilated everything else to itself. As the heroic legend with all its manifold discrepancies was easily developed into the tranquil fulness and light variety of epic poetry, so afterwards it readily responded to the demands which the tragic writers made upon it for earnestness, energy, and compression; and whatever in this sifting process of transformation fell out as inapplicable to tragedy, afforded materials for a sort of half sportive, though still ideal representation, in the subordinate species called the _satirical drama_.
I hope I shall be forgiven, if I attempt to illustrate the above reflections on the essence of Ancient Tragedy, by a comparison borrowed from the plastic arts, which will, I trust, be found somewhat more than a mere fanciful resemblance.
The Homeric epic is, in poetry, what bas-relief is in sculpture, and tragedy the distinct isolated group.
The poetry of Homer, sprung from the soil of legend, is not yet wholly detached from it, even as the figures of a bas-relief adhere to an extraneous backing of the original block. These figures are but slightly raised, and in the epic poem all is painted as past and remote. In bas- relief the figures are usually in profile, and in the epos all are characterized in the simplest manner in relief; they are not grouped together, but follow one another; so Homer's heroes advance, one by one, in succession before us. It has been remarked that the _Iliad_ is not definitively closed, but that we are left to suppose something both to precede and to follow it. The bas-relief is equally without limit, and may be continued _ad infinitum_, either from before or behind, on which account the ancients preferred for it such subjects as admitted of an indefinite extension, sacrificial processions, dances, and lines of combatants, &c. Hence they also exhibited bas-reliefs on curved surfaces, such as vases, or the frieze of a rotunda, where, by the curvature, the two ends are withdrawn from our sight, and where, while we advance, one object appears as another disappears. Reading Homer is very much like such a circuit; the present object alone arresting our attention, we lose sight of that which precedes, and do not concern ourselves about what is to follow.