Hylas: Yes, Philonous, I grant the existence of a sensible thing consists in beingperceivable, but not in being actually perceived. Philonous: And what is perceivable but an idea? And can an idea exist without being actually perceived? Bach's compositional solutions were based in large part on rhetorical components. Such components were based in classical rhetorical theory, rhetoric being one of the other major artforms affected by humanist thought. Read Bach and the Harmonia Mundi (PDF), a paper I wrote for MUSC 433 at CWRU in 1999.