The life of Bertrand Russell, born when Queen Victoria had nearly three decades still to reign, was one of the most influential of thetwentieth century, as well as one of the most controversial. He resolved to write two series of books 'in the philosophy of the sciencesand 'on social and political questions ; and for the next three quarters of a century he switched from one to the other in an astonishing range of publications which gave him a position unique amongother Englishmen of his time. But the Bertrand Russell of A History of Western Philosophy,the man who put an 'absolute unbridled Titanic passion' into Principia Mathematica, was also a controversial figure on the world stage. He served two prison sentences: the first during the 1914-18 war for making'statements likely to prejudice His Majesty's relations with the UnitedStates of America', the second in 1961, in his 90th year, for inciting the public to civil disobedience. Russell's personal life was as turbulent as his public activities. With the most famous of his mistresses, Lady Ottoline Morrell, he found a 'kind of restfulness and sense of home-coming in her 'aristocratic habits of mind', but he also married no less than four times.