The thought of Karl Jaspers does not reveal an evolution in the sense of an intellectual pilgrimage whose stages and whose course could be precisely defined. In a certain sense, as he says himself, his philosophy was already immanent in him by the time he was seventeen. He is not one of those who wait for problems to run up against them from the outside. Events in the world, hypotheses and ideas are indeed the object and the matter of his reflection, but they are summoned from within to serve as props for a different kind of confrontation, at once more essential and more mysterious, whose mystery must be illuminated without being dispelled. His attitude is meditative. His thought digs deep, but digs on the spot; its end is an experience always the same yet inexhaustible, alongside which every sort of diversity appears monotonous. That is why vertical images bulk so large in his vocabulary, the vocabulary of a diviner: sources, gushing forth, the abyss, the ground that one loses or recovers, and a complete ambiguity about depth and height which imposes and refuses transcendence.