outside the play; but it may be within it, like the act of the Alcmeon
in Astydamas, or that of the Telegonus in _Ulysses Wounded_. A third
possibility is for one meditating some deadly injury to another, in
ignorance of his relationship, to make the discovery in time to draw
back. These exhaust the possibilities, since the deed must necessarily
be either done or not done, and either knowingly or unknowingly.

The worst situation is when the personage is with full knowledge on
the point of doing the deed, and leaves it undone. It is odious and
also (through the absence of suffering) untragic; hence it is that no
one is made to act thus except in some few instances, e.g. Haemon and
Creon in _Antigone_. Next after this comes the actual perpetration of
the deed meditated. A better situation than that, however, is for the
deed to be done in ignorance, and the relationship discovered
afterwards, since there is nothing odious in it, and the Discovery
will serve to astound us. But the best of all is the last; what we
have in _Cresphontes_, for example, where Merope, on the point of
slaying her son, recognizes him in time; in _Iphigenia_, where sister
and brother are in a like position; and in _Helle_, where the son
recognizes his mother, when on the point of giving her up to her
enemy.

This will explain why our tragedies are restricted (as we said just
now) to such a small number of families. It was accident rather than
art that led the poets in quest of subjects to embody this kind of
incident in their Plots. They are still obliged, accordingly, to have
recourse to the families in which such horrors have occurred.

On the construction of the Plot, and the kind of Plot required for
Tragedy, enough has now been said.