Modes and modal systems (groups of related modes) are none other than generalized types of melodic movement occurring in folk music, both vocal and instrumental. Arising first in folk song, they become fixed in the scaling of folk musical instruments, in the linear measurements that determine the structure of intervals. The chief types of instruments with fixed scaling are wind instruments with finger-holes, and fretted stringed instruments of the lute family. Whereas the human voice and lutes-without-frets belong (potentially at least) to the realm of free melodic creativity, musical instruments with fixed scales preserve historical stages in the development of melody, of individual modes and of entire modal systems. The scaling of an instrument is indeed a kind of notation; its symbols are not written on paper but exist as linear proportions on the instrument itself.