Poetics (9.11c-10.2)

But this is bad work,

For in that way the incidents will cause more amazement than if they happened mechanically and accidentally, since the most amazing accidental occurrences are those which seem to have been providential, for instance when the statue of Mitys at Argos killed the man who caused Mitys’s death by falling on him at a festival. Such events do not seem to be mere accidents.

So such plots as these must necessarily be the best.

Some plots are simple and some complex, as indeed the actions represented by the plots are obviously such.

By a simple action I mean one that is single and continuous in the sense of our definition above,[*] wherein the change of fortune occurs without reversal or discovery;