I Capture the Castle guests describe each other in terms of famous artists. Topaz is called a work by William Blake, Rose is said to resemble Emma, Lady Hamilton, the muse of the painter George Romney, Simon says that Cassandra is like "Girl with a Mousetrap," a painting by Joshua Reynolds, and Mrs Fox-Cotton is said to be a work by Salvador Dalí "with snakes coming out of her ears". Simon introduces Cassandra to the works of Claude Debussy: "Clair de lune", "La cathédrale engloutie", "La terrasse des audiences du clair de lune". She also listens to J. S. Bach's "Sheep May Safely Graze"
Au clair de la lune Anderson and William March write: "A few days later, in the same apartment. The living-room is empty: Rhoda can be seen practicing 'Au Clair de la Lune' on the piano in the den." Au clair de la lune "" (, lit. "By the Light of the Moon") is a French folk song of the 18th century. Its composer and lyricist are unknown. Its simple melody () is commonly taught to beginners learning an instrument. Some sources report that "plume" (pen) was originally "lume" (an old word for "light" or "lamp"). 19th-century French composer Camille Saint-Saëns quoted the first few notes