Abu Rayhan al-Biruni (973–1048) was a polymath from Khwarezm whose interests spanned astronomy, mathematics, geography, history and mineralogy. He calculated the radius of the Earth with remarkable precision, speculated about its rotation long before European scholars, and — having learned Sanskrit and studied local customs — produced a detailed account of India. Over his lifetime he wrote around a hundred and fifty works, remaining a model of the scholar for whom no question was forbidden.