At the time of his death in May 1961, Maurice Merleau-Ponty held the chair of Philosophy at the College de France. Together with Jean-Paul Sartre and Simone de Beauvoir, he was cofounder of the successful and influential review Les Temps Modernes. However, after Merleau-Ponty's two studies of Marxist theory and practice (Humanisme et Terreur and Les Aventures de la Dialectique), he alienated both orthodox Marxists and "mandarins of the left" such as Sartre and de Beauvoir. Perhaps his most lasting contribution to the interpretation of human existence was his formulation of a positive philosophical approach to psychology the foundations of which were clearly outlined in The Structure of Behavior and later more fully developed in Phenomenology of Perception.