This book being something of a confession…’, says Jean Piaget in a footnote of Insights and Illusions, in which he goes on to describe an encounter with ‘the great Bergson’. The book is indeed an intensely personal one, and this, more even than its polemics with diverse philosophical psychologists (or psychologizing philosophers) is what gives it both its charm and its interest. It reminds one very strongly of R.G.Collingwood’s Autobiography. A lady novelist once claimed that Russell told her that talking to her was more exciting than making love to other women. Whether or not we credit her story, there is no doubt that when a Piaget or a Collingwood confesses his doctrinal flirtations, the result is considerably more interesting than the accounts of other men’s amours.