The blues arose, largely undocumented, in the Deep South before the Civil War. The music sprang out of chants, work songs and field hollers — plantation slaves calling back and forth to one another. Later, the story gets complicated. Musicologists continually are discovering new cross cultural influences.

About 100 years ago, the blues settled into a form and style of music that has many variations — Piedmont Blues, Delta Blues, Memphis Blues, Chicago Blues, Urban Blues and more.

But the beauty of the blues is that the music is simple, powerful and makes perfect sense upon a first listening.

Here are the basics of the blues:

Most blues songs are built on 12 measures of music, following a loosely prescribed order of underlying harmony. That is called a chord progression, combinations of three or more notes played together — the chords that give richness and depth to the melody — the tune. If you know a little about music, the blues is built on the I, IV and V chords.

The melody is expressive and uses blue notes, notes not found on the "do, re, mi, fa, so, la, ti, do" Western scales we all learned as children. If you look at a piano keyboard, the blues player is using notes between the keys. More technically, these are flattened third and especially fifth and seventh notes on a major scale.

In order to play blues notes on the piano, you have to crush two keys together.

If you play the guitar or any stringed instrument, you bend the strings.

If you bend the strings right, you get a guitar voice (sound) eerily close to the human voice. The overwhelming affiliation of guitar with the blues evolved because a solo composer-singer-player can call out a lyric and musically match and respond on the guitar.

That is "call and response," a key element in the blues.

Put another way, remember those 12 measures of music? Divide them into groups of four. Sing over the first two measures, then respond instrumentally in the following two measures. Repeat. Repeat again.

Blues lyrics are sad, funny, resigned, stoic and deeply human.

They are roughly written in iambic pentameter, the same rhythmic beat of much of Shakespeare who — like a bluesman — was a popular artist, delving the human heart.

The stanzas of a blues song usually follow an AAB pattern. The blues songs starts with the A line, a line of lyrics and melody that states the issue. Then the A line is repeated.

The A lines are followed by a variant on the melody and a different lyric, the B line, which offers comment, a course of action or resolution to the original plaint.

That, really, is all you need to know. But then there is this:

When I was younger, I suffered some fairly serious losses. I toughed through the teaching year and, at a time when the dollar was strong and airfares cheap, I took myself to the South of France. There was a lot of art to see and the Grande Parade de Jazz Festival was running in Nice.

One night at the festival, I was part of a largely French audience. They were chanting Bee, Bee — BEE, BEE — BEE BEE KING. It was twilight in an olive grove, and B.B.King was taking the stage. And, as I heard the blues live and really listened, for maybe the first time, I knew I would be OK