defined as the working out of the Divine will in society; hence it
requires a crisis of humanity as its subject, it involves the conflict
of a higher with a lower civilization, and it is conducted by means of a
double plot, one in heaven, the other on earth. These are the
characteristic epic traits. In dealing with ideas of such importance,
the poets in successive eras of civilization naturally found much
adaptation to new conditions necessary, and met with ever fresh
difficulties; the result is a many-sided epic development. The idea of
the Divine will, the theory of its operation, and the conception of
society itself were all subject to change. Epics at first are
historical; but, sharing with the tendency of all art toward inwardness
of meaning, they become purely spiritual. The one thing that remains
common to all is the notion of a struggle between a higher and a lower,
overruled by Providence. They have two subjects of interest, one the
cause, the other the hero through whom the cause works; and between
these two interests the epic hovers, seldom if ever identifying them and
yet preserving their dual reality.

The Iliad has all the traits that have been mentioned, but society is
still loose enough in its bonds to give the characters free play; it is,
in the main, a hero-epic. The Aeneid, on the contrary, exhibits the
enormous development of the social idea; its subject is Roman dominion,
which is the will of Zeus, localized in the struggle with Carthage and
with Turnus, but felt in the poem pervasively as the general destiny of
Rome in its victory over the world; and this interest is so overpowering
as to make Aeneas the slave of Jove and almost to extinguish the other
characters; it is a state-epic. So long as the Divine will was conceived
as finding its operation through deities similar to man, the double plot
presented little difficulty; but in the coming of Christian thought,
even with its hierarchies of angels and legions of devils, the