In chamber music from the Baroque period, the written parts for keyboard instruments -- the harpsichord and the organ, for example – often consisted of merely a bass line, with numbers written under the notes. Such a bass line was called a “figured bass,” and the numbers, or figures, indicated which chords the keyboard player was expected to fill in above the bass, while at the same time improvising melodies [or countermelodies] to go along with what the other instruments were playing. The