A musician and an architect, Richard Wagner and Gottfried Semper, two German artists, influenced the theory of art in the nineteenth century in Germany. Wagner met Semper in a music shop and later they participated in various discussions regarding the history and theories of art and they both held their own perspectives. Wagner developed the theory of Gesamtkunstwerk in Germany, based on the integration of music, dance, and poetry, while Semper worked on the integration of music and architecture based on the common character of proportion and scale. This dissertation traces the evolution of this theory in nineteenth century Germany, introducing each person's perspective while summarizing the synthesis of the notion of the arts at the end, aiming to develop a general perception of its function in art. In addition, Semper expanded the notion of mathematics in art by exploring and bringing the example of natural forms and patterns. For him, mathematics had been categorized into three aspects of Symmetry, Proportionality, and Movement. In addition, movement and direction for him were the beginning of the exploration of Vitruvius's idea of eurhythmy. Semper brought the example of the human body as a reference for measuring and scaling the architectural drawings. This research focused on three crucial questions and the discovery of Semper's work, Second Dresden Theater. First, it investigated the connection between Semper's architectural drawing and musical notation. Second, it scrutinized the attitude toward the integration of arts among artists and philosophers in nineteenth century Germany. Third, it explored the role played by