Short, extremely perceptive discussions about ``meaning'' and ``understanding'' in serious music that will captivate new listeners as well as the musically tuned-in. Readers who can set aside their envy of Rosen's talents--he is a renowned pianist on stage and recordings, a persuasive advocate of new music, and a world-class prose stylist (The Classical Style won a National Book Award in 1972)--will devour these three lectures that Rosen gave in Rome last year under the aegis of the New York Review of Books. For wit, intelligence, and original thought about the problems of how to speak (or write) cogently about classical masterpieces as well as the challenging musical art of today, Rosen has few rivals. He starts with a large enough question: ``What does it mean to understand music?'' Expanding his first ``modest'' definition that ``understanding music simply means not being irritated or puzzled by it,'' he goes on to suggest that the historical evolution of musical criticism began with judgment (i.e., deciding how a musical piece measures up to accepted classical models or, more generally, to listeners' unconscious expectations) and in the last 200 years was transformed into an imaginative exercise in comprehension. Given the radical leaps in musical language taken by 20th-century composers, Rosen's investigation of changing critical criteria is especially pertinent for the contemporary listener who, sorely tried, is still trying to understand modern music. Rosen does rely on some musical examples printed in the text, but an inability to read musical notation will not measurably diminish the reader's pleasure in following his train of thought. Not every reader will agree with all of Rosen's notions, particularly his Mahler-esque maxim that ``the name generally given to widely accepted error is tradition.'' Still, few music lovers will come away unsatisfied. A work of genuine intellectual nourishment, brief but brilliant.