In this entertaining and authoritative biography Michael Sharratt examines the flair, imagination, hard-headedness, clarity, combativeness, and penetration of Galileo Galilei. To follow his career as he exploited unforeseen opportunities to unseat established ways of comprehending nature is to understand a crucial stage of the Scientific Revolution. Galileo was a path-breaker for the newly-invented telescope, the decoder of nature's mathematical language, and a quite brilliant populariser of science. Even his reluctant excursion into theology has at last been officially and handsomely recognised by the Church's 'rehabilitation' of the Inquisition's most famous victim, fully discussed in the last chapter. This book makes his lasting contributions accessible to non-scientists and his mistakes are not overlooked. This is not a mythical story, but the biography of an innovator - one of the greatest ever known.