imitation is one when the object imitated is one, so the plot, being an
imitation of an action, must imitate one action and that a whole, the
structural union of the parts being such that, if any one of them is
displaced or removed, the whole will be disjointed and disturbed. For a
thing whose presence or absence makes no visible difference, is not an
organic part of the whole.



IX

It is, moreover, evident from what has been said, that 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
work of Herodotus might be put into verse, and it would still be a
species of history, with metre no less than without it. 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. By the universal, I mean how a person of a certain type will
on occasion speak or act, according to the law of probability or
necessity; and it is this universality at which poetry aims in the names
she attaches to the personages. The particular is--for example--what
Alcibiades did or suffered. In Comedy this is already apparent: for here
the poet first constructs the plot on the lines of probability, and then
inserts characteristic names;--unlike the lampooners who write about
particular individuals. But tragedians still keep to real names, the
reason being that what is possible is credible: what has not happened we
do not at once feel sure to be possible: but what has happened is