This is the 3rd edition of Professor Piston's classic, now in its 5th edition. While designed to teach the theory of musical harmony to college music majors, it is useful for anyone studying a musical instrument. (Mine was the piano) It covers tonality, harmonic progression, modulation and many, many chords. (Diminished 7th, anyone? Augmented 6th?) Exercises included for each chapter. If you can read music, you can read this book.