Like Bártok, Hindemith or Messiaen, whose music Julius Juzeliūnas (1916-2001) regarded as examples for his own work the composer developed his own composition system. Intense intellectual work and a change in political situation influenced his move from national romanticism to modernism in early 1960s. Like a true structuralist Juzeliūnas plunged into studies of Lithuanian folk music looking for typical melodic patterns, basic tones, their regular repetitions and relationships. On this basis he created his system of harmony, modal in character, which was set out in his doctorate On the Structure of the Chord, and consistently implemented in his creative work. Julius Juzeliūnas for many years was one of the leading composition teachers and his intellectual approach to the composition process has influenced generations of composers.