Basso Continuo, Ground Bass, and Figured Bass

What is basso continuo, and what does it do?

Think about it this way. Basso continuo, which traditionally was made up of two instruments — a bass instrument like the viol, and a keyboard instrument like the harpsichord — was like a rhythm section. The continuo instruments kept the beat and outlined the harmonic changes.

In twentieth-century musical genres like jazz, rock, and reggae, the rhythm section keeps a steady beat which holds the music together. Over this rhythmic and tonal framework, the solo instruments are able to improvise.

For instance, Billie Holiday’s trio keeps a steady rhythmic and harmonic beat, allowing her to come in with her vocal entrances very late (but she always catches up — a hallmark of her style):

The Wailers’ rhythm section does the same thing, allowing Bob Marley to improvise, using his vocals as a solo instrument:

Note the basso continuo (viola da gamba and harpsichord) here, and pay attention to the musical motif they play. It’s called a ground bass.

A famous example of ground bass is Dido’s lament, “When I am laid in earth,” from the opera Dido and Aeneas by Henry Purcell (1689). Pay attention to the bass clef in this piano-vocal transcription:

Another well-known ground bass with which you may be familiar:

This is an example of a score that a continuo player might play from:

It’s not all that different from the lead sheet that a jazz player might use on a gig: