In the 1950s and early 1960s, two main schools of criticism laid claim to Pollock's work. Clement Greenberg and his followers saw the "drip" pictures as dematerialized veils of color. Other critics, such as Harold Rosenberg and Allan Kaprow, interpreted the marks on canvas as traces of a private dance or ritual. In the 1970s and 1980s, critics analyzed Pollock's early work for evidence of Jungian archetypes, and explored his significance as an unwitting tool of Cold War propaganda. Other recent writers have linked him to Surrealist ideas of formlessness and bodily symbolism.