Karl Jaspers died in 1969, leaving unfinished his universal history of philosophy, a history organized around those philosophers who have influenced the course of human thought. The first two volumes of this work appeared in Jasper's lifetime; the third and fourth have been gathered from the vast material of his posthumous papers. This is the fourth volume. Following his original plan of "promoting the happiness that comes of meeting great men and sharing in their thoughts," Jaspers discusses Descartes, a pious Catholic who vacillated between rational philosophy and obedience to authority. Lessing, whose thought was clear, open-ended, experimental, hones. Pascal. Kierkegaard, Nietzsche, and Weber, who posed most penetratingly and urgently the "radical questionability of human Existenz." Marx was a dogmatic dreamer, and Einstein a great scientist, but limited in his insight into human existence. Jasper's method is personal, one of constant questioning and struggle, as he enters into dialogue iwth his "eternal contemporaries," the thinkers of the past. For he believes that it is only through communication with others that we come to ourselves and to wisdom.