INTRODUCTION I approached my seventy-fifth birthday the thought occurred to me of excluding all writers who were younger than myself But this appeared a rather egocentric cut-off point So finally I opted for a thirty-year rule, and have excluded works written after 1975 I must ask the reader to bear in mind that this is the final volume of a history of philosophy that began with Thales It is accordingly structured in rather a different way from a self-standing history of contemporary philosophy I have, for instance, said nothing about twentieth-century neoscholastics or neo-Kantians, and have said very little about several generations of neo-Hegelians To leave these out of a book devoted to the philosophy of the last two centuries would be to leave a significant gap in the history But the importance of these schools was to remind the modern era of the importance of the great thinkers of the past A history that has already devoted many pages to Aquinas, Kant, and Hegel does not need to repeat such reminders As in writing previous volumes, I have had in mind an audience at the level of second- or third-year undergraduate study Since many undergraduates interested in the history of philosophy are not themselves philosophy students, I have tried not to assume any familiarity with philosophical techniques or terminology Similarly, I have not included in the Bibliography works in languages other than English, except for the original texts of writers in other languages Since many people read philosophy not for curricular purposes, but for their own enlightenment and entertainment, I have tried to avoid jargon and to place no difficulties in the way of the reader other than those presented by the subject matter itself But, however hard one tries, it is impossible to make the reading of philosophy an undemanding task As has often been said, philosophy has no shallow end I am indebted to Peter Momtchiloff and his colleagues at Oxford University Press, and to two anonymous readers for the Press who removed many blemishes from the book I am also particularly grateful to Patricia Williams and Dagfinn Føllesdal for assisting me in the treatment of twentieth-century Continental philosophers xv