One of the real classics of Expressionism -- even the Americans think so, to judge from the fact that they've remade it (badly) several times. To be sure, the premise won't stand examination (but then, it's horror), and a modern viewer may find it hard to adjust to the actors' Expressionist grimacing. However, the movie is consistently suspenseful due to its heavy dark atmosphere and communication of mental torment. The fear of one's own body is a dynamite theme if it's as well presented as it is here.