Pythéas of Marseille

Upon his return, Pytheas recounted his voyage in two books that have now disappeared: “Description of the Earth” and “On the Ocean”. Their dissemination in the Greek world received a mixed reception. Scientists made extensive use of his measurements, while the majority of historians and geographers in the Roman world were much more nuanced towards him.

Pytheas is back in Marseille. He brings back in his luggage and in the holds of the Artemis, amber, and tin; no doubt also craft objects from the countries he has visited. And we can imagine what the reactions of his entourage were. First of all, for the rich city of Massalia, Pytheas says that deliveries of tin from English Cornwall will continue. The Garonne route is safe, and that of the Seine and the Rhône becomes so again, the Celts are stabilizing. For amber, it is a little more complicated because there is only the Rhine route. He will have to wait a little longer to benefit from regular supplies. He is greeted with relief by the Timuks and the rich merchants of the city. The prosperity of the city is assured.

And then there are all the wonderful and extraordinary stories he tells. Indeed, he went to the edge of the ocean, where for the majority of his fellow citizens, nothing exists anymore. We can imagine the crew (if there was one) recounting the voyage in the taverns of the port in front of an astonished audience. The evenings must have been long!

But Pytheas, the scientist, has other ideas in mind. Faced with the accumulation of such discoveries, he cannot remain silent. So he writes two books: "Description of the Earth" and "Of the Ocean".

The first relates his journey on foot beyond Gaul to Britannia and Thule.

The second, recounts his sea voyage aboard his ship, on the edge of Europe (1). These are Cosmas Indicopleustes for On the Ocean (M48.1) on the one hand and Apollonius for Description of the Earth (Q79) on the other hand, who cite these works. 

According to some specialists, the first title is the generic term for any book dealing with geography and science. The second is the particular title. 

When did he write them, and therefore when did he leave? We know that Herodotus, who wrote between 335 and 323 BC, knew Massalia, but did not cite Pytheas. Therefore, the voyage was not known at that time or, at least, the writings did not yet exist. The first to cite Pytheas are, on the one hand, a disciple of Aristotle between 326 and 296 BC, and Timaeus between 320 and 300. We can therefore consider that it was around 320 BC that the books of Pytheas were introduced into the Greek world. It took about five years for them to be written and then distributed. It was therefore around 330/310 BC that Pytheas made his journey. Some authors even specify 312

This table shows us the astronomical measurements that Pytheas made during his journey. When he goes up north, he observes increasingly longer days (at the summer solstice, and in modern times). In some cases we know the estimated distance measurements, in latitude, with Massalia. The third column gives the latitudes measured by Pytheas, converted into degrees. These measurements are provided to us by Hipparchus. From the two previous columns, it is very easy to give - fourth column - the measurement of the circumference of the earth according to Pytheas. We can observe that, from an estimate of the distance between Marseille and three points in the north, our friend Pytheas provided low measurements of the circumference of the earth (except for one measurement). Hats off to you, Mr. Pytheas. These measurements of the circumference of the earth by Pytheas do not appear anywhere. This is simply because at the time of Hipparchus – around 140 BC – the circumference was known and Pytheas’ measurement was no longer of interest.

The great library of Alexandria opened its doors in 295 BC. It contained over 500,000 volumes at its peak, and its catalogue included 120 books. Eratosthenes was its chief librarian and he made extensive use of Pytheas’ information. Another library, in competition with Alexandria, existed at Pergamum, on the coast of Asia Minor. It is reasonable to assume that On the Ocean was also present there. It was transferred to Alexandria during the reign of Mark Antony.

Is it possible to imagine what effect Pytheas’ books had on readers? A sort of modern Odyssey where the magical and the extraordinary are constantly present. So extraordinary and so disturbing that some authors, the best known of whom is Strabo and whose manuscripts modern historians are less and less sure he had in his hands, will outright deny the exploits of Pytheas.

What did he bring us?

A maritime exploration without precedent for the time. A scientific expedition of the highest interest. A reassuring commercial mission for the Phocaean city and the Greek world. Pytheas, a man from Marseille, of whom Bougainville said that he was "a skilled astronomer, an ingenious physicist, an exact geographer, a bold navigator", was an explorer ahead of his time. He was also the first polar explorer.