It happened round about midnight a week ago, when I was rewatching the last segment of Ken Burns’s classic production of “Jazz” on PBS.

Trumpeter and jazz historian Wynton Marsalis, while explaining the incredible popularity of jazz in the decades following the Great Depression, when it accounted for some 70 percent of all records sold, went on to describe its fall to a low point of 3 percent, or near extinction.

My aha! moment came a few minutes later. But first a few bars of background information.

I’ve been a lover of jazz since my high school days, which younger readers might locate somewhat after the Middle Ages but before the advent of seat belts. I recall agonizing over joining the Columbia Record Club, torn between the worry of financing an occasional LP record and an almost hypnotized attraction to the music of pianist Dave Brubeck and his alto sax man Paul Desmond, and the pure foot-tapping fun of listening to Louis Armstrong.

Brubeck and Armstrong won out, thank goodness. If they hadn’t I’d no doubt be richer financially, but the net worth of my life would be much the poorer.

My early fascination with the cool sounds of Brubeck and Desmond led on to a vast treasure of musical gold as minted by people like Miles Davis and J. J. Johnson and Kai Winding and Gerry Mulligan and Oscar Peterson and Dizzy Gillespie and Charley Parker and John Lewis and Ella Fitzgerald and Jelly Roll Morton and Sarah Vaughn and Duke Ellington and John Coltrane and Ornette Coleman and Mary Lou Williams and Herbie Hancock and Nat King Cole and Billie Holiday and Nina Simone and certainly Thelonius Monk.

But that’s just a few off the top of my head.

From them I learned invaluable lessons. Right off the bat I learned that jazz musicians judged each other by how well you could play your horn or sing your song. Little else mattered, including the pigmentation of your skin.

Jazz musicians were loving and marrying across racial lines right from the get-go and seemed to understand that much of what passed for respectability was based more on fear than compassion.

Somehow jazz sliced through lots of pretensions and got down to the heart of things. At the center of it was the ability to listen to one another and trade ideas back and forth. To do this, you had to learn to improvise, to play your music on the run, to change things around if they didn’t make sense.

I soon learned that most jazz musicians played their music in bars or clubs or concert halls to make a living, but afterward got together in private to jam. A jam session might get sorta nasty, when one horn player tried to “cut” another by playing a riff or a passage faster or louder or more smoothly than his opponent.

But it also fostered plenty of learning and delight. Sitting near each other in the same room allowed you to read each other accurately - and that’s when the light bulb in my head turned on.

Jazz began to die, at least in part, when electronic advances revolutionized the recording industry. Recording was broken into individual musicians laying down “tracks” while alone. The bassist might never see the drummer or the pianist or the horn player till after the recording was done.

With this change, the chance to interact evaporated. And with it, some of the fun of playing music.

Might we be suffering a parallel fate today? When we talked on the phone or got a written letter in the mail, we could hear Aunt Mabel’s voice or see the quality of her handwriting, and with that came some insights.

Now we text on our cell phones or email on computers and never really jam together.