Five early prominent 20th-century philosophers to directly address the effects of modern technology on humanity were John Dewey, Martin Heidegger, Herbert Marcuse, Günther Anders and Hannah Arendt. They all saw technology as central to modern life, although Heidegger, Anders,[6] Arendt[7] and Marcuse were more ambivalent and critical than Dewey. The problem for Heidegger was the hidden nature of technology's essence, Gestell or Enframing which posed for humans what he called its greatest danger and thus its greatest possibility.