 "The Dreams in the Witch House" was likely inspired by Willem de Sitter's lecture "The Size of the Universe," which Lovecraft attended three months prior to writing the story.De Sitter is mentioned by name in the story, described as a mathematical genius, and listed in a group of other intellectual masterminds, including Albert Einstein.Several prominent motifs—including the geometry and curvature of space and using pure mathematics to gain a deeper understanding the nature of the universe—are covered in both Lovecraft's story and de Sitter's lecture.