This new investigation of the Brandenburg Concertos explores musical, social, and religious implications of Bach's treatment of eighteenth-century musical hierarchies. By reference to contemporary music theory, to alternate notions of the meaning of 'concerto', and to various eighteenth-century conventions of form and insturmentation, the book argues that the Brandenburg Concertos are better understood not as an arbitrary collection of unrealted examples of 'pure' instrumental music, but rather as a carefully compliled and meaningully organized set. It shows how Bach's concertos challenge (as opposed to reflect) existing musical and social hierarchies.