The Greek Geographer Who Preserved Most of What We Know About Eratosthenes by Citing Him to Disagree With Him

Strabo of Amaseia (c. 64 BC – c. 24 AD) was a Greek geographer and historian who spent most of his adult life either at Rome (under Augustan-period imperial patronage) or at Alexandria (during a substantial extended visit between approximately 25 and 20 BC). His major surviving work is the Geographika — a seventeen-book systematic geography of the inhabited world as the late Hellenistic Greek tradition understood it.

The Geographika is the last great Hellenistic geographical synthesis to survive substantially intact. Its closest predecessor, Eratosthenes’s three-book Geographika of approximately 220 BC, is lost. Strabo’s work is therefore one of the principal surviving sources for Eratosthenes’s geographical method.

Strabo cited Eratosthenes substantially in order to disagree with him.

What Strabo wrote

The Strabonic Geographika opens with two extended methodological books (Books I and II) and then proceeds through fifteen books of detailed regional description: Iberia and the western Mediterranean (Book III), Gaul and Britain (Book IV), Italy (Books V–VI), northern and central Europe (Book VII), the Greek mainland and islands (Books VIII–X), Asia Minor and the Black Sea (Books XI–XII), the Caucasus and Persia (Books XIII–XV), Mesopotamia and Arabia (Book XVI), Egypt and North Africa (Book XVII).

The methodological books — substantively the most cited and most influential portion of the work — are organised as an extended critique of the prior Hellenistic geographical tradition. Strabo addresses Homer, Hecataeus of Miletus, Herodotus, Aristotle, Pytheas of Massalia, Dicaearchus, Eratosthenes, Hipparchus, Polybius, and Posidonius — the complete list of major prior Hellenistic geographical authorities. Eratosthenes receives by far the most extended treatment.

Why he disagreed

Strabo’s substantive methodological objection to Eratosthenes was that Eratosthenes had treated geography substantively as a mathematical and astronomical discipline (the substantive ‘mathematical geography’ tradition of computed positions, sphere-of-the-earth models, and astronomically-derived coordinates) rather than as a substantively descriptive-narrative discipline (the substantive ‘chorographic’ tradition of place-based description for the use of administrators, generals, and travellers).

Strabo’s preferred framework was the chorographic one. He substantively considered the precise mathematical-astronomical computation of geographical positions to be substantively irrelevant for practical purposes — the substantive Eratosthenes Earth-circumference computation from the Syene shadow was, on Strabo’s view, an academic exercise that produced no useful administrative or military information. The substantive chorographic alternative — substantively detailed descriptions of regional landscapes, peoples, customs, and economic resources — was substantively more valuable to the Roman imperial administrative class that Strabo was substantively writing for.

What he preserved

The paradox of the Strabonic critique is that Strabo cited Eratosthenes so extensively in the course of disagreeing with him that the Geographika is now the principal surviving source for the substantive Eratosthenian geographical framework. Approximately 150 substantive Eratosthenes passages survive only through Strabonic quotation; the outline of the Eratosthenes three-book Geographika is reconstructable substantively only from the Strabonic critique.

The substantive Eratosthenes Earth-circumference computation, the Eratosthenian theory of zones (the substantively five climatic zones — torrid, two temperate, two frigid — that Eratosthenes had developed from his Earth-sphere framework), the Eratosthenian estimates of distances between major Mediterranean cities, and the substantive Eratosthenian world-map (the first systematic Greek attempt at a coordinated world map): all of these substantively survive only through Strabo.

The irony of Strabo’s geographical legacy is that the work that substantively rejected the mathematical-astronomical geographical tradition substantively became the principal vehicle for its survival. Strabo died at Amaseia around 24 AD, aged approximately 88. His Geographika substantively had no significant influence on the immediately following Roman geographical tradition (Pliny the Elder, writing two generations later, appears not to have read it) but substantively dominated Byzantine geographical scholarship from the 10th century onwards and substantively shaped European Renaissance geographical thought after the 1469 first Latin translation by Guarino Veronese.