The visual arts and music already began to draw on one another in the nineteenth century, insofar as painters strove to depict movement, for example, while program music alluded to paintings. But it was only at the start of the twentieth century, in the course of the theoretical debate on a synthesis of the arts, that a transfer of structural modes of creative production took place. In the visual arts, this first became manifest in the integration of a temporal dimension derived from musical practice, then in an orientation based on rhythmic and harmonic relationships, and principles of composition and improvisation. Music, in turn, began to address color, surface, and artistic techniques.