Many 20th century artists explored existentialist themes in their work as a response to how industrialization had changed society and humanity's place in the world. Notable artists who reflected existentialist ideas include Cézanne through his simplified forms, Van Gogh through themes of emptiness and isolation in works like "Night Cafe", and Picasso in his depiction of the horror of war in "Guernica". Overall, existentialist art emphasizes the individual experience in a world that can be hostile or indifferent.