In 1907 he published his "The North Italian Painters of the Renaissance", where he expressed a devastating and still controversial judgement of Mannerist art, which may be related to his love for Classicism and his professed distaste for Modern Art. His early works were later integrated in his most famous book, "The Italian Painters of the Renaissance" (1930), which was widely translated and reprinted. He also published two volumes of journals, "Rumor and Reflection" and "Sunset and Twilight". He is also the author of "Aesthetics and History" and "Sketch for a Self-portrait".