The Philosophy of Schopenhauer by Bryan Magee
This is thought to be the most comprehensive treatment of Schopenhauer's philosophy to have appeared in English. It contains a brief biography of the philosopher, a systematic exposition of his thought, and a critical discussion of the problems to which it gives rise and of its influence on a wide range of philosophers and artists. Of special interest is its extended treatment of the influence of Schopenhauer on Wagner and Wittgenstein.