Aristotle Rhetoric 3.16.11

[11] Again, the narrative should be introduced in several places, sometimes not at all at the beginning. In deliberative oratory narrative is very rare, because no one can narrate things to come; but if there is narrative, it will be of things past, in order that, being reminded of them, the hearers may take better counsel about the future. This may be done in a spirit either of blame or of praise; but in that case the speaker does not perform the function of the deliberative orator. If there is anything incredible, you should immediately promise both to give a reason for it at once and to submit it to the judgement of any whom the hearers approve; ¹ as, for instance, Jocasta in the Oedipus of Carcinus ² is always promising, when the man who is looking for her son makes inquiries 20 of her; and similarly Haemon in Sophocles. ³