The sole opera of Dimitris Mitropoulos, Soeur Beatrice, after a text by Maiterling, closes a period of development of the melodramatic production in Greece, which took place in the first 20 years of this century. Around that period, a great number of composers take advantage of a unique historical juncture and compose works that, on the one hand, carry on the melodramatic production of the Eptanesian school of the 19th century, on the other hand, create the preconditions for further development all over the country.During his adolescence Dimitris Mitropoulos is influenced by his teacher at the Conservatory of Athens, A. Marsick. Thus, his musical language is shaped mainly by the musical idiom of C. Franck. He is also influenced by the music of R. Wagner and C. Debussy. What is really impressive, however, is the assimilative potential of the young composer, as well as the morphological consistency shown in his opera, a work which has been considered an important contribution to the development of Greek Opera.