Martin Heidegger, was the German philosopher who wrote Being and Time. He was one of the most influential philosophers of the 20th century, and his ideas have penetrated into many areas. His discussion of ontology has led to his being often cited as one of the founders of existentialism. His ideas inspired major philosophical works, e.g., Sartre's Being and Nothingness, although Heidegger insisted that Sartre misunderstood him. His philosophical work was taken up throughout Germany, France, and Japan and has gained, since the 1970s, a fair following in North America as well. Heidegger's work was scorned and dismissed, however, by many of his contemporaries, such as the Vienna Circle, Theodor Adorno, the Hegelians, and Anglo-American philosophers such as Bertrand Russell and A. J. Ayer.