  Although Du Bos was primarily concerned with poetry and painting, he made a significant contribution to philosophy of music. He was an advocate of the resemblance theory of musical expression. According to this theory, music is expressive of emotions because it resembles human expressive behavior. This view is found, in the contemporary world, in Davies (1994) and Kivy (1980). (See the article on Philosophy of Music, 3.1.) Music can resemble either vocal or non-vocal expressive behavior. It can resemble, for example, the plodding steps of a sad person or the joyful cries of a happy one. Because music resembles such expressive behavior, it is heard as sad, joyful, or expressive of some other emotion.