Quodlibet

A quodlibet is a piece of music which combines several different melodies in counterpoint, usually popular tunes, and often in a light-hearted manner. A very famous example of a quodlibet is at the end of Bach's Goldberg Variations. Another example is Galimathias Musicum, a 17 part quodlibet composed by Wolfgang Amadeus Mozart when he was about 10 years old.

More serious quodlibets can be found in the masseses of Jacob Obrecht, which sometimes combine popular tunes, plainsong and original music at once.