Editing Eratosthenes (section)

==Life==
The son of Aglaos, Eratosthenes was born in 276 BC in [[Cyrene (city)|Cyrene]]. Now part of modern-day [[Libya]], Cyrene had been founded by Greeks centuries earlier and became the capital of [[Pentapolis (North Africa)]], a country of five cities: Cyrene, [[Tocra|Arsinoe]], [[Berenice]], [[Ptolemais, Cyrenaica|Ptolemias]], and [[Apollonia, Cyrenaica|Apollonia]]. [[Alexander the Great]] conquered Cyrene in 332 BC, and following his death in 323 BC, its rule was given to one of his generals, [[Ptolemy I Soter]], the founder of the [[Ptolemaic Kingdom]]. Under Ptolemaic rule the economy prospered, based largely on the export of horses and [[Silphium (antiquity)|silphium]], a plant used for rich seasoning and medicine.<ref name="roller"/> Cyrene became a place of cultivation, where knowledge blossomed. Like any young Greek at the time, Eratosthenes would have studied in the local [[Gymnasium (ancient Greece)|gymnasium]], where he would have learned physical skills and social discourse as well as reading, writing, arithmetic, poetry, and music.<ref name="bailey" />
[[File:Eratosthenes Teaching in Alexandria (Bernardo Strozzi, Montreal).jpg|thumb|''Eratosthenes teaching in Alexandria'' by [[Bernardo Strozzi]] (1635)]]

Eratosthenes went to Athens to further his studies. There he was taught [[Stoicism]] by its founder, [[Zeno of Citium]], in philosophical lectures on living a virtuous life.<ref name="rist" /> He then studied under [[Aristo of Chios]], who led a more [[Cynicism (philosophy)|cynical]] school of philosophy. He also studied under the head of the [[Platonic Academy]], who was [[Arcesilaus of Pitane]]. His interest in [[Plato]] led him to write his first work at a scholarly level, ''Platonikos'', inquiring into the mathematical foundation of Plato's philosophies.<ref name="chambers" /> Eratosthenes was a man of many perspectives and investigated the [[Poetry|art of poetry]] under [[Callimachus]].<ref name="bailey" /> He wrote poems: one in [[hexameter]]s called ''Hermes'', illustrating the god's life history; and another in [[elegiac]]s, called ''Erigone'', describing the suicide of the Athenian maiden [[Erigone (daughter of Icarius)]].<ref name="chambers" /> He wrote ''Chronographies'', a text that scientifically depicted dates of importance, beginning with the [[Trojan War]]. This work was highly esteemed for its accuracy. [[George Syncellus]] was later able to preserve from ''Chronographies'' a list of 38 kings of the [[Egyptian Thebes]]. Eratosthenes also wrote ''Olympic Victors'', a chronology of the winners of the [[Olympic Games]]. It is not known when he wrote his works, but they highlighted his abilities.

These works and his great poetic abilities led the king [[Ptolemy III Euergetes]] to seek to place him as a librarian at the [[Library of Alexandria]] in the year 245 BC. Eratosthenes, then thirty years old, accepted Ptolemy's invitation and traveled to Alexandria, where he lived for the rest of his life. Within about five years he became Chief Librarian, a position that the poet [[Apollonius Rhodius]] had previously held. As head of the library Eratosthenes tutored the children of Ptolemy, including [[Ptolemy IV Philopator]] who became the fourth Ptolemaic pharaoh. He expanded the library's holdings: in Alexandria all books had to be surrendered for duplication. It was said that these were copied so accurately that it was impossible to tell if the library had returned the original or the copy.
He sought to maintain the reputation of the Library of Alexandria against competition from the [[Library of Pergamum]]. Eratosthenes created a whole section devoted to the examination of [[Homer]], and acquired original works of great tragic dramas of [[Aeschylus]], [[Sophocles]] and [[Euripides]].<ref name="chambers" />

Eratosthenes made several important contributions to [[mathematics]] and [[science]], and was a friend of [[Archimedes]]. Around 255&nbsp;BC, he invented the [[armillary sphere]]. In ''On the Circular Motions of the Celestial Bodies'',<ref>{{Cite web|title=Aratus's "Phenomena," Cleomedes's "On the Circular Motions of the Celestial Bodies," and Nichomachus's "Introduction to Arithmetic" – Viewer – World Digital Library|url=https://www.wdl.org/en/item/14757/view/1/1/|access-date=2021-02-24|website=www.wdl.org}}</ref> [[Cleomedes]] credited him with having calculated the [[Earth's circumference]] around 240 BC, with high accuracy.<ref name="russo273277" />

Eratosthenes believed there was both good and bad in every nation and criticized [[Aristotle]] for arguing that humanity was divided into Greeks and [[barbarian]]s, as well as for arguing that the Greeks should keep themselves racially pure.<ref name="alexander" /> As he aged, he contracted [[ophthalmia]], becoming blind around 195 BC. Losing the ability to read and to observe nature plagued and depressed him, leading him to voluntarily starve himself to death. He died in 194&nbsp;BC at the age of 82 in Alexandria.<ref name="bailey" />