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).