 Why did Humphrey decorate with a moon, neon roses, and music?
Fownes stopped on the porch to brush the plaster of paris off his shoes. Or, as Fownes hoped it might appear, the illusion of the domed city vanished and was replaced by a more satisfactory, and, for his specific purpose, more functional, illusion. The sun and moon both looked down upon a garden that was itself scintillant, composed largely of neon roses. He watched as the moon played, Oh, You Beautiful Doll and the neon roses flashed slowly from red to violet, then went back to the closet and turned on the scent. Undiminished, the yellow moon and the red sun continued to be brilliant, although the sun occasionally arced over and demolished several of the neon roses.
 to seduce Mrs. Deshazaway
 to give Mrs. Deshazaway something that looked like her past  to seduce Mrs. Deshazaway  he was trying to decorate his home uniquely  these were items he had read about from the past