'Incubus' is one of a series of paintings which Hume based on swing doors found in schools and hospitals. These paintings are largely monochromatic. Painted in pale-coloured household gloss, they incorporate circles, squares and rectangles to represent the windows and panels of actual doors. They appear abstract, and yet they accurately represent real doors. Hume used housepaint to make the connection even more literal. He also liked the reflective surface the paint gave the works: '..it reflects the environment which the works are shown in.. everything would be reflected within the painting, including yourself...So they made you think about light and about where the paintings begin and end.'