AMONG THE POTENTIAL attractions of Gingerich's study of Nicolaus Copernicus's De Revolutionibus Orbium Coelestium and its readers is its alluring multinational band of leading characters. First there is Copernicus himself, a busy Polish canon, doctor and lawyer who took so long - more than thirty years - to get his idea of a sun-centred cosmos into print that he was on his deathbed when it appeared in 1543. Then there's his disciple Rheticus, which coaxed him into publishing but went unacknowledged in the book and ended his academic career in disgrace after a homosexual scandal. Tycho Brahe was a peppery Dutch aristocrat whose observations were crucial to the new astronomy, although he drew the wrong conclusions from them. Johannes Kepler, a German, was forced to earn a living as imperial astrologer while using Brahe's work to turn Copernicus' hypothesis into a system. Finally there's Galileo Galilei, the polymathic genius humiliatingly summoned to Rome after indicating support for the heliocentric heresy.

To which can be added a colourful supporting cast including Giordano Bruno and John Dee, plus any number of popes and princes. And all against the historical backdrop of a Europe fissured by religious coflict and clashes between individual conscience and authority: a context which directly impinged on the progress