Usually it conformed to one of a few patterns, the most common being "On seeing..." (ιδών or cum vidisset), "On being asked..." (ἐρωτηθείς or interrogatus), and "He said..." (ἔφη or dixit).
The following chreia,[2] the most common in ancient sources,[3] is illustrative: μικταὶ δὲ αἱ μῖξιν ἔχουσαι λόγου καὶ πράξεως, οἷον ‘Διογένης ἰδὼν μειράκιον ἀτακτοῦν τὸν παιδαγωγὸν ἐτύπτησε λέγων· τί γὰρ τοιαῦτα ἐπαίδευες;’ On another hand, ‹chreiai› that contain a mixture of theory and practice are mixed, such as 'Diogenes, on seeing a youth misbehaving, struck his paedagogus, adding "Why do you teach such things?"'
Chreiai could be silly: Olympias, on hearing that her son Alexander was proclaiming himself the offspring of Zeus, said "Won't this fellow stop slandering me to Hera?
"Or all of these: Socrates the philosopher, when a certain student named Apollodorus said to him, "The Athenians have unjustly condemned you to death," responded with a laugh, "But did you want them to do it justly?
The student would praise, paraphrase, explain, contrast, compare, provide an example, make a judgment, and, in conclusion, exhort the reader.