Run the Gamut

This one comes straight from medieval music theory. Around the turn of the 11th century, the monk Guido of Arezzo developed a system for naming musical notes using the syllables ut, re, mi, fa, sol, and la, the ancestor of today's do-re-mi. The lowest note recognised in the system was called "gamma ut," combining the Greek letter gamma with "ut," and this contracted into "gamut," meaning the full range of notes a voice or instrument could produce. By the 1620s, "gamut" meant the whole musical scale in general use, and "run the gamut," covering the entire range from one extreme to the other, followed naturally from there.