The Complete Aristotle (eng.)

follows It is,
therefore, never, or very rarely, found in poetry. One instance,
however, is in the Antigone, where Haemon threatens to kill Creon.
The next and better way is that the deed should be perpetrated.
Still better, that it should be perpetrated in ignorance, and the
discovery made afterwards. There is then nothing to shock us, while
the discovery produces a startling effect. The last case is the
best, as when in the Cresphontes Merope is about to slay her son,
but, recognizing who he is, spares his life. So in the Iphigenia,
the sister recognizes the brother just in time. Again in the Helle,
the son recognizes the mother when on the point of giving her up.
This, then, is why a few families only, as has been already
observed, furnish the subjects of tragedy. It was not art, but
happy chance, that led the poets in search of subjects to impress
the tragic quality upon their plots. They are compelled, therefore,
to have recourse to those houses whose history contains moving
incidents like these.
    Enough has now been said concerning the structure of the
incidents, and the right kind of plot.
XV
    In respect of Character there are four things to be aimed at.
First, and most important, it must be good. Now any speech or
action that manifests moral purpose of any kind will be expressive
of character: the character will be good if the purpose is good.
This rule is relative to each class. Even a woman may be good, and
also a slave; though the woman may be said to be an inferior being,
and the slave quite worthless. The second thing to aim at is
propriety. There is a type of manly valor; but valor in a woman, or
unscrupulous cleverness is inappropriate. Thirdly, character must
be true to life: for this is a distinct thing from goodness and
propriety, as here described. The fourth point is consistency: for
though the subject of the imitation, who suggested the type, be
inconsistent, still he must be consistently inconsistent. As an
example of motiveless degradation of character, we have Menelaus in
the Orestes; of character indecorous and inappropriate, the lament
of Odysseus in the Scylla, and the speech of Melanippe; of
inconsistency, the Iphigenia at Aulis—for Iphigenia the suppliant
in no way resembles her later self.
    As in the structure of the plot, so too in the portraiture of
character, the poet should always aim either at the necessary or
the probable. Thus a person of a given character should speak or
act in a given way, by the rule either of necessity or of
probability; just as this event should follow that by necessary or
probable sequence. It is therefore evident that the unraveling of
the plot, no less than the complication, must arise out of the plot
itself, it must not be brought about by the Deus ex Machina—as in
the Medea, or in the return of the Greeks in the Iliad. The Deus ex
Machina should be employed only for events external to the
drama—for antecedent or subsequent events, which lie beyond the
range of human knowledge, and which require to be reported or
foretold; for to the gods we ascribe the power of seeing all
things. Within the action there must be nothing irrational. If the
irrational cannot be excluded, it should be outside the scope of
the tragedy. Such is the irrational element the Oedipus of
Sophocles.
    Again, since Tragedy is an imitation of persons who are above
the common level, the example of good portrait painters should be
followed. They, while reproducing the distinctive form of the
original, make a likeness which is true to life and yet more
beautiful. So too the poet, in representing men who are irascible
or indolent, or have other defects of character, should preserve
the type and yet ennoble it. In this way Achilles is portrayed by
Agathon and Homer.
    These then are rules the poet should observe. Nor should he
neglect those appeals to the senses, which, though not among the
essentials, are the concomitants of poetry; for here too there is
much room for error. But of this enough has been said in our
published treatises.
XVI
    What Recognition is has been already explained. We will now
enumerate its kinds.
    First, the least artistic form, which, from poverty of wit, is
most commonly employed—recognition by signs. Of these some are
congenital—such as ‘the spear which the earth-born race bear on
their bodies,’ or the stars introduced by Carcinus in his Thyestes.
Others are acquired after birth; and of these some are bodily
marks, as scars; some external tokens, as