Several writers have attempted to map the parameters of avant-garde activity. The Italian essayist Renato Poggioli provides one of the earliest analyses of vanguardism as a cultural phenomenon in his 1962 book Teoria dell’arte d’avanguardia (The Theory of the Avant-Garde). Surveying the historical, social, psychological and philosophical aspects of vanguardism, Poggioli reaches beyond individual instances of art, poetry, and music to show that vanguardists may share certain ideals or values which manifest themselves in the non-conformist lifestyles they adopt: He sees vanguard culture as a variety or subcategory of Bohemianism. Other authors have attempted both to clarify and to extend Poggioli’s study. The German literary critic Peter Bürger’s Theory of the Avant-Garde (1974) looks at the Establishment’s embrace of socially critical works of art and suggests that in complicity with capitalism, “art as an institution neutralizes the political content of the individual work”.