Four decades ago, a new discipline began to develop in American universities, the so-called 'Philosophy of Music'. But why was that label chosen? When was it used for the first time? In what context did it happen? Philosophers have paid no attention to the history of the expression, which is also the history of a philosophical idea, and most of the early sources are virtually unknown. They are essential to understanding what 'philosophy of music' is. I study the history of the expression from a philosophical perspective, trying to understand its birth and its survival to this day.