Circumference: Chapter 4

And we hear it in Aristotle, when he supposedly advised the young Alexander “to have regard for the Greeks as for friends and kindred, but to conduct himself toward other peoples as though they were plants or animals.” Alexander should do so because “the barbarians are more servile in their nature than the Greeks, and the Asiatics than the Europeans, [enduring] despotic rule without any resentment.”

In addition to Eratosthenes’s heterodox philosophy and the irritating comprehensiveness of his interests, he apparently took a dim view of the ethnic prejudices of most educated Greeks.

...Alexander, disregarding his advisers, welcomed as many as he could of the men of fair repute and did them favors — just as if those who have made such a division, placing some people in the category of censure, others in that of praise, did so for any other reason than that in some people there prevail the law-abiding and the political instinct, and the qualities associated with education and powers of speech, whereas in other people the opposite characteristics prevail!

Certainly such views were profoundly subversive: the rationale for Greco-Macedonian hegemony over Alexander’s former domains was, after all, rooted in Greek superiority in the arts of civic life.

The only original measurement — or in current experimental parlance, the “critical manipulation” — therefore lay in ascertaining the sun’s angle at Alexandria.

We see a similar effect when a straight object looks bent when one end is placed obliquely in a swimming pool.

This was a practical necessity in a place sustained by annual flooding of the Nile, which regularly changed both the contours and extent of the arable — and taxable — land around it.

One explanation for the discrepancy is that Cleomedes opted to report a rounded-off figure, possibly because his treatise was pitched to an undiscriminating audience.

After the death of Alexander an alphabetic scheme superseded the acrophonic everywhere except Athens.

In a world where arithmetic was cumbersome and scratch paper expensive, avoiding cumbersome figures was not sloppy — it represented the better part of prudence.

...the length of Eratosthenes’s stade may be determined by two alternative methods; the first is to accept the ancient evidence for Eratosthenes’s use of the Attic stade...and the second is to arbitrarily assert that the evidence is wrong and invent our own stade.

His map, though more accurate in certain respects, propagated the ancient fable that Asia and Africa were linked by a vast, undiscovered, and wholly fictive southern continent.

Philopator’s two closest advisors were capable, unscrupulous men: the first, Sosibius of Alexandria, had first risen to prominence as an athletic champion in mainland Greece, and held the title of chief priest of the cult of Alexander; the second, Agathocles of Samos, had known Philopator since childhood, and was the brother of Agathocleia, the new king’s mistress.

For my gnomon, I planned to use the most prominent vertically plumb object in the city: the ninety-eight-foot-high granite monolith known as Pompey’s Pillar.

The sole insult inflicted by time has been a persistent misnomer: the Pillar was raised in honor of the Roman emperor Diocletian in 291 CE, and has nothing at all to do with Pompey.