Hypnosis (1904) by Sascha Schneider, which came to my attention from watching The Lighthouse (2019)
Robert Eggers, writer and director, has experience as a production designer and it was interesting to learn how much the artwork represented in the film also reflects other themes.
That's kinda satisfying for a former film studies major.
Here's a poster for the film showing how Schneider's image was interpreted for the story of two lonely men maintaining a large phallic symbol.