Critique of Dialectical Reason, originally Critique de la raison dialectique (1960), was the last of Jean-Paul Sartre's major philosophical works: it attempted to reconcile Marxism and Existentialism building on Search for a Method, an earlier essay that became the introduction for the Critique. By using events of the French Revolution and other historical occasions (including the notion that the endowment by Europeans of certain metals with a "precious" value led inexorably to slavery), Sartre attempted to show how what we call class is a special instance of a human grouping, or rather several levels of human groupings (seriality). He preceded this with complex explanations of groupings of increasing sophistication, ranging from a queue at a bus stop to institutions.