At the heart of the extraordinary ferment of the High Renaissance stood a distinctive, strange and beguiling figure: the magus. An unstable mix of scientist, bibliophile, engineer, fabulist and fraud, the magus ushered in modern physics and chemistry while also working on everything from secret codes to siege engines to magic tricks.Anthony Grafton's wonderfully original book discusses the careers of men who somehow managed to be both figures of startling genius and - by some...