Herodotus' construction of authority is a process that spans the whole of the Histories. The sweeping expanses of the text's claims to truth and knowledge are traced and defended throughout all nine books. If certain key passages function as cornerstones of the massive narrative edifice, a great many other sections of the Histories contribute in asserting the "demonstration of enquiry" offered by the author to his audiences. Our understanding of Herodotean authority is constantly changing as we refine the tools of interrogation at our disposal; at some twenty-five centuries of distance, the debates that sharpen our disagreements about the nature of the epistemic project pursued by the Histories will continue to transform what is read into Herodotus' voice (see e.g. Marincola 1987; Nagy 1988; Campos Daroca 1992; Thomas 2000; De Jong 2001; Chamberlain 2001; Kindt 2006; Marrucci 2009). The bulk of the scholarly discussion on the matter tends to return to the same programmatic passages of explicit narratorial intervention from Books 1 and 2, with most other sections of the Histories seen as applications of those programmes. What I propose to do in this paper is revisit the process of Herodotean authority through a passage that can neither be read as programmatic nor reduced to the echo of another programmatic directive: the Histories' engagement with the work and the biographical tradition of Aristeas of Proconnesus at the beginning of Book 4 (on Aristeas, see e.g. Bowra 1956; Bolton 1962; Dowden 1980; Huxley 1986; Ivantchik 1993). Herodotus' investigation of ta makrotata in 4.5-36 is woven over the rival legacy of Aristeas in a deep web of contestations and appropriations unlike any other intertextual dialogue found in the Histories. The meanings inscribed by Herodotus on the peoples and the vast territories north of the Black Sea, and the radical rewriting of the Hyperborean presence at the heart of the Greek world proposed by the Histories, are thoroughly intertwined with that confrontation between the historian and the author of the Arimaspea. After looking at the specificities of Herodotus' engagement with Aristeas in 4.5-36, the paper will proceed to discuss the roles played by this staging of opposition in the text's construction of authority at that moment in the narrative. It will then examine the points of contact and contrast that link the Herodotean presentation of Aristeas with the roles played by the figures of Hecataeus, Homer, and Hesiod in the larger architecture of the text as a whole (on Herodotus and Hecataeus, see e.g. Armayor 1987; West 1991; Fowler 2001; Dewald 2002; Moyer 2002).