The scientists at the end of the 19th century had people coming to them with this weird behaviour, and they didn't know what was going on but there seemed to be a similarity. They needed an answer, so they made up one. ↗
I think every age has a medium that talks to it more eloquently than the others. In the 19th century it was symphonic music and the novel. For various technical and artistic reasons, film became that eloquent medium for the 20th century. ↗