This chapter considers a number of different elements within Michael Finnissy’s work and compare them with the same elements in the work of a range of other composers, focusing especially on subject matter, form and musical materials. The profuse invention that is so characteristic of all Finnissy’s work can sometimes suggest that the principal subject of his music is music itself. At its heart, Finnissy’s music is essentially modernist in its interrogation of subject matter, form and materials, but the conclusions reached are radically different from those to be found in much of the music of his contemporaries. As with electronic sound and sound-processing, Finnissy, however, has shown remarkably little interest in this newly revealed instrumental sound world, in spite of working closely with many of its leading practitioners. More importantly, the fundamentals of Finnissy’s musical language are at odds with much of the post-1970s thinking about tuning and temperament.