There are those who consider that studies in harmony, counterpoint, and fugue are the exclusive province of the intended composer. But if we reflect that theory must follow practice, rarely preceding it except by chance, we must realize that musical theory is not a set of directions for composing music. It is rather the collected and systematized deductions gathered by observing the practice of composers over a long time, and it attempts to set forth what is or has been their common practice. It tells not how music will be written in the future, but how music has been written in the past. The results of such a definition of the true nature of musical theory are many and important. First of all, it is clear that this knowledge is indispensable to musicians in all fields of the art, whether they be composers, performers, conductors, critics, teachers, or musicologists. Indeed, a secure grounding in theory is even more a necessity to the musical scholar than to the composer, since it forms the basis for any intelligent appraisal of the individual styles of the past or present. On the other hand, the person gifted for creative musical composition is taking a serious risk in assuming that this genius is great enough to get along without a deep knowledge of the common practice of composers. Mastery of the technical or theoretical aspects of music should be carried out by him as a life's work, running parallel to his creative activity but quite separate from it. In the one he is following common practice, while in the other he is responsible solely to the dictates of his own personal tastes and urge for expression. Walter Piston (Intro to the first edition of *Harmony*) --