Eratosthenes

I was born at Cyrene and schooled in Athens, where philosophy and letters tempered my measures with verse. Ptolemy III summoned me to Alexandria; in time I kept the keys of the Library. Some called me Pentathlos, others "Beta"—second in many arts. I accepted the taunt; breadth, not vanity, was my discipline.

At the summer solstice I noted that at Syene a plumb line met no shadow, yet in Alexandria a gnomon cast one. The angle was near a fiftieth of the circle. Taking the road distance—bematists reckoned five thousand stadia between the two—I multiplied. Thus came 250,000 stadia, later set as 252,000 so each degree could count 700.

In my Geography I gathered reports fit for reason, not merely for song. I set parallels and meridians upon the oikoumene, marked climatic zones, and weighed sailors’ tales against calculation. Homer I revered as a poet, not a map.

I sifted numbers with a sieve to leave primes clean; I fashioned a mesolabe to find mean proportionals; I judged the Sun’s obliquity; I dated wars and games in a Chronographia. Much I wrote is lost, and rumor paints my old age blind. Believe this instead: I tested words by measures and measures by words.