On Music and Sound

Music is the science of sounds; consequently Sound is the principal object of Music.

Music is ordinarily divided into Harmony and Melody, although the latter is only a part of the former, and it suffices to know Harmony in order to be perfectly instructed in all the properties of Music, as will be shown in what follows.

We shall leave to Physics the task of defining Sound; in Harmony one distinguishes it only as grave or acute, without regard to its force or its duration; and it is upon the relationship of acute sounds to grave ones that all the knowledge of Harmony must be founded.

Grave sounds are the lowest, such as those produced by male voices, and the acute are the most elevated, such as those produced by female voices.

One calls Interval the distance there is from one grave sound to an acute sound, and the different distances that can be found between one sound and another form different intervals, whose degrees take their denomination from the numbers of Arithmetic; thus the first degree can be denominated only by unity, whence one calls two sounds on the same degree Unison, and consequently the second degree is called Second, the 3rd Third, the 4th Fourth, the 5th Fifth, the 6th Sixth, the 7th Seventh, the 8th Octave; and so on — supposing that the first degree is always the most grave, and that the others are formed by raising the voice successively according to its natural degrees.