Mieczysław Wallis (1895-1975) authored 18 books, including 15 monographs in art history, the major ones being Autoportret (Self-Portrait, 1964), Poznna tworczosc wielkich artystów (The Late Works of Great Artists, 1975) and Secesja (Art Nouveau, 1967). Also worth noting is Sztuki i znaki. Pisma semiotyczne (Arts and Signs. Semiotic Writings, 1983). The main contribution of M. Wallis to art history lies in his modern metahistorical reflections, which are based on the firmly held beliefs about close relations between art history and other fields of art and aesthetics. His recommended method is moderate historiosophical relativism. Wallis recognizes within the process of reception the important role that scientific discourse and cultural paradigm play. In Secesja he used the iconological method, combining art with the philosophical and scientific thought of the Belle Epoque. In his analyses of medieval art he introduced the semiotic method, having successfully avoided the constraints characteristic of semiological studies. A philosophy of art history which assumes the variability of forms, of aesthetic sensibility and of knowledge does not necessarily lead to an extreme relativism, but accepts artistic pluralism; it allows us to retain the view on the continuity of art towards the avant-garde. Wallis interpreted its variable character by distinguishing between soft and sharp aesthetic values. Wallis laid the basis for an original, interdisciplinary approach to art. However, the distance that separated him from the aesthetics focused on the work of art itself, as well as from the social history and ideological criticism which were opposed to it, was the reason for his ideas to remain outside the mainstream of academic art history and aesthetics.