My subject is the ‘Dorieus episode’, chapters 42–8 of Book 5 of Herodotus. They deal with the late sixth-century western adventures of the Spartan prince Dorieus, half-brother of King Cleomenes. This piece of narrative is, remarkably enough if there is anything in the biographical tradition associating Herodotus with Thurii, one of only three main sections in Herodotus which cover west Greek affairs in any detail, using ‘west Greek’ to mean Italy and Sicily. The others are, first, the story of the Samians at Zancle, the later Messina (6.23–5), and, second, the excursus prompted by the Greek approach to Gelon for help in 480 bc (7.153–71). This ends with material about Rhegium and Taras which Herodotus explicitly and apologetically calls ‘an insertion into his account’, λ⋯γου παρενθ⋯κη. This general Herodotean parsimoniousness about Italy and Sicily may have prompted Thucydides' contemporary Antiochus of Syracuse (FgrH 555) to write a history of the west in Ionic Greek. The choice, by this Dorian writer, of Ionic, the Greek of ethnography down to Nearchus of Krete and beyond, was a way of saying, ‘I am doing what Herodotus did not; I am filling a Herodotean gap.’

Herodotus' seven chapters about Dorieus of Sparta are rich and precious. They are positioned roughly at the centre of the nine-book Histories, and my object in the present study is to try to locate them in the architecture of Book 5 and of the whole work.