Sacrobosco was a cosmographer and monk who lived and worked in Paris. He taught astronomy at the University of Paris and his writings became fundamental parts of the curriculum for centuries.

He is believed to have been born in northern England and may have studied at Oxford University. He is best remembered for two major scientific contributions: his introduction of the Hindu-Arabic numerical system, which became the standard text on arithmetic; and his criticism of the 

Remarkably, Sacrobosco anticipated reforms similar to those of the Gregorian calendar more than 300 years before their adoption.

An engraving showing a bearded man holding an armillary sphere