In the wake of "Being and Nothingness", Sartre became concerned to reconcile his concept of freedom with concrete social subjects and was strongly influenced in this regard by his friend and associate Maurice Merleau-Ponty, whose writings in the late 1940s and early 1950s (such as "Sense and Non-Sense") were pioneering a path towards a synthesis of existentialism and Marxism. Merleau-Ponty, however, then became increasingly skeptical of Marxism, culminating in his "Adventures of the Dialectic" (1955), while Sartre continued to grow more engaged with Marxist thought. Though Sartre had, by 1957, decisively broken with the Soviet Union and "official" Marxism in the wake of the Soviet suppression of the Hungarian uprising, he nonetheless declared Marxism "the philosophy of our time" and stated the need to resuscitate it from the moribund state that Soviet dogma had left it in, a need he attempted to answer by writing "Critique of Dialectical Reason". The conflict between Sartre and Merleau-Ponty on this issue ended their long-standing friendship, though Ronald Aronson states that, in part, "Critique of Dialectical Reason" was Sartre's answer to his former friend and political mentor's attack on Marxism.