Science has spread from western Europe where it developed into recognisably-modern form in the seventeenth century, stimulated by Copernicus’s claim that the Earth is a planet. Copernicus however was an astronomer in the Greek tradition, whose task was to reproduce the planetary paths by geometrical constructions using uniform circular motions. Eudoxus’s attempt to do this with nests of concentric spheres had been superseded by the use of the more flexible techniques necessary to meet the observational standards of the Hellenistic era. Ptolemy’s Almagest synthesised the Greek achievement but its shortcomings led Copernicus to make the Earth a planet.