Fernando Lopes-Graca's importance to 20th-century Portuguese music cannot be overestimated. His study of native songs and traditions has been compared to that of Bartok, and the soulful melodies of the Tr�s cancoes corais are an early example of his highly effective integration of folk style into rigorous historically established forms. From the reverence and purity of the Christmas Cantata songs to the harmonic density of the Tr�s liricas castelhanas de Camoes, the powerful and often deeply moving combination of Lopes-Graca's use of classical structure alongside his country's musical heritage finds it's zenith in his writing for voices.