In 1872, in a backroom of the British Museum, a man called George Smith spent the darkening days of November bent over a broken clay tablet. It was one of thousands of fragments from recent excavations in northern Iraq, and was covered in the intricate cuneiform script that had been used across ancient Mesopotamia and deciphered in Smith's own lifetime. 

Some of the tablets set out the day-to-day business of accountants and administrators - a chariot wheel broken, a shipment of wine delayed, the prices of cedar or bitumen. Others recorded the triumphs of the Assyrian king's armies, or the omens that had been divined by his priests in the entrails of sacrificial sheep. 

Smith's tablet, though, told a story. A story about a world drowned by a flood, about a man who builds a boat, about a dove released in search of dry land.