Pity, Terror, and Peripeteia

In an article (C.Q. xli [1947], 73 ff.) based on an unpublished paper by Professor Cornford, Mr. I. M. Glanville returned to the suggestion that the words at the beginning of Chapter 11 of the Poetics (1452a23), which are part of the definition of peripeteia, refer back to the phrase (52a4), thereby raising the question whose expectation it is to which events turn out contrary, that of the audience or of the characters in the play.