meter. He is only insisting that imitation in unmetrical language is still
poetry; that meter is not the characteristic element of poetic.[16] It is
important to recognize that in classifying poetry with music and dancing,
Aristotle is insisting that the common element in these arts is movement.
Movement is characteristic of poetry, as color and form are characteristic
of painting and sculpture. Thus in discussing the plot of tragedy, which
he holds to be the highest and most characteristic form of poetry,
Aristotle urges the necessity of unity and magnitude, both of which he
defines in terms not of space relations, but of movement. For instance, to
possess unity a plot must have a beginning, a middle and an end.

A beginning is that which does not itself follow anything by causal
necessity, but after which something naturally is or comes to be. An
end, on the contrary, is that which itself naturally follows some other
thing, either by necessity, or as a rule, but has nothing following it.
A middle is that which follows something as some other thing follows
it.[17]

Furthermore, the magnitude which this dramatic movement should possess is
also discussed not in terms of bulk, but of length.

As, therefore, in the case of animate bodies and organisms, a certain
magnitude is necessary, and a magnitude which may be easily embraced in
one view; so in the plot, a certain length is necessary, and a length
which can easily be embraced by the memory.[18]

It is noteworthy that to Aristotle the characteristic movement of poetic
depends on the dramatic unity and progression of a dramatic action, a
plot. In the _Rhetoric_ he shows that the arrangement of the movement of a
speech is governed by entirely different considerations. The unity of