Reading Carl Sagan is great shortcut to an enrapturing sense of wonder about the universe, the earth, and knowledge in general. In Cosmos - his best known work - he gives a survey of all the natural sciences, and much history. If you've never watched or read it, it's worth your time and attention. If you already have, it's worth revisiting. 

Here's a quick portrait of the Great Library of Alexandria, which flourished two thousand years ago, paraphrased from Sagan's presentation. 

The heart of the library, naturally, was its book collection, estimated to number half a million volumes, on the subjects of mathematics, physics, biology, astronomy, literature, philosophy, geography and medicine, each one a hand copied scroll. Agents bought the contents of libraries from abroad. Commercial ships in the harbour of Alexandria were boarded and searched - not for contraband, but for scrolls, which were all taken, copied, and returned to their owners. 

The original manuscripts of the great Greek playwrights Sophocles, Aeschylus and Euripides, numbering hundreds of plays, were borrowed from the city of Athens in exchange for an enormous cash deposit. They were copied, and the copies were returned, not the originals, deliberately forfeiting the deposit.

The library, as Sagan describes, "contained ten large research halls, each devoted to a separate subject; fountains and colonnades; botanical gardens; a zoo; dissecting rooms; an observatory; and a great dining hall where, at leisure, was conducted the critical discussion of ideas."

The art of critical editing was invented in this library. The Old Testament is known to us today largely thanks to the Greek translations made in the Alexandrian Library. 

Its scholars included Eratosthenes, who theorized the Earth was round, and correctly calculated its circumference, arguing that if you sailed west from Spain, you could reach India. Hipparchus figured out that stars come into being, slowly move over the course of centuries, and burn out. Aristarchus of Samos wrote that the earth is a planet which orbits the sun, and that the stars are tremendously distant. Euclid produced a textbook on geometry that helped spur the scientific curiosities of Kepler, Newton and Einstein. Heron of Alexandria invented gear trains and steam engines and wrote the first book on robots. Herophilus established that the brain is the seat of intelligence, not the heart. 

The last scientist who worked in the great library was Hypatia, a mathematician, astronomer, physicist and head of the Neoplatonic school of philosophy, a woman who moved freely through what were considered masculine domains, in a time when women had very little freedom and were often treated as property (a great beauty as well, she rejected all offers of marriage). She was born in 370 CE, and was despised by Cyril, Archbishop of Alexandria, due to her friendship with the Roman governor and her status as a symbol of learning and science, disciplines the early Christian church associated with paganism. Despite personal danger, she published and taught till 415, when a mob of Cyril's parishioners dragged her from her chariot and flayed her skin from her body with abalone shells. Her works were burned, as was the Great Library soon after. Cyril was named a saint. 

[note: there are alternate details given for the library's destruction on wikipedia]

"It was as if the entire civilization had undergone some self-inflicted brain surgery, and most of its memories, discoveries, ideas and passions were extinguished irrevocably. The loss was incalculable."

The struggle between knowledge and fear continues today. May we all add our efforts to the perpetuation of knowledge. As Sagan said: "I think the health of our civilization, the depth of our awareness about the underpinnings of our culture and our concern for the future can all be tested by how well we support our libraries."