Variations (music)
Composers have used variations in music for centuries.  In the Renaissance and Baroque periods composers wrote variations on a short tune in the bass which was repeated again and again.  This was called a ground bass or sometimes it was a passacaglia or chaconne.  Renaissance composers also liked writing what they called “divisions”.  This meant varying a tune by playing it, for example, at twice the speed or half the speed etc. so that crotchets (quarter notes) became minims (half notes) or quavers (eighth notes).