In the seventeenth century science moved from the alchemy and astrology of John Dee to the observation and astronomy of Galileo, from the classicism of Aristotle to the evidence-based, collegiate investigation of Francis Bacon. And if the old ways still lingered, affecting the new mind set - Descartes' dualism, an attempt to square the new philosophy with religious belief; Newton, the man who understood gravity and the laws of motion, yet fascinated to the end of his life by alchemy - by the end of that tumultuous century 'the greatest ever change in the mental outlook of humanity' had irrevocably taken place.