In a striking theoretical re-positioning, Barbara Barry proposes that problem-solving, as in scientific theory, asks strategic questions of “how” and “why” important musical compositions work the way they do. She focuses on three criteria of investigation: identity, implementation and intrusion, in order to define normative frameworks of style and form. These normative constructs provide frames of reference by which to evaluate powerful innovation in music, and in larger contexts of art, literature and the history of ideas.