In the field of Western art music, improvisation has become a much discussed topic. In this interdisciplinary study Bert Mooiman argues that in this context, improvisation is not to be seen as a quasi-autonomous skill or art form, but as an aspect of music-making in general. With this research, Mooiman offers a ‘panorama’ of nineteenth-century styles and situations of music-making that together sketch a picture of improvisatory aspects of nineteenth-century music. Music was generally experienced as a wordless language, and he argues that making music was understood as a rhetorical act: performers strove for musical persuasion. This study focuses on the performer: it explores how performers in the nineteenth century might have thought during the real-time act of music-making, and how performers today might learn to use musical languages from the past actively again. For this last aspect, the area of music theory is relevant; Mooiman concludes his dissertation with a discussion of how traditional music theory is challenged by improvisatory music-making.