Chs 13 and 14 of the Poetics contain Aristotle's central thoughts about the tragic plot; both have provoked much debate. Chs 13 in particular has been especially influential. The first possibility, in which the terrible act is knowingly planned, but not done, is quickly rejected. But Aristotle seems right to say that this form of plot was rarely used; the example given, Haemon's plot against his father Creon, was in fact only a subplot of Sophocles' Antigone. The second possibility is that in which the terrible act is knowingly planned and done. This would seem to describe a large amount of significant tragedy, including for instance the stories of Alcmaeon and Orestes. The third possibility is where a terrible act is done unknowingly, followed by recognition, typically of the agent's relationship with the victim.