In August, I squeezed into a packed house at The Hang to soak up the incredible musicianship of the Jazz Camp faculty band. At one point, Jimmy Greene was taking a solo, the band solid bedrock under him. His big tenor sax sound was rocketing around the room, muscular and searching and clear as honey. Suddenly he was way up in the highest register of the horn. There’s a pinch up there, an ache in the sound that tore right through me and illuminated everything—the performers in their various roles, the musical maneuvering that had led them there, the brilliance of this art form.

What grabbed me in Jimmy’s solo was not the sweetness or agility, but that sudden eruption of something gritty, elemental, unrestrained. It was a perfect example of the thing that happens in all kinds of art—the juncture between expectation and surprise, when our own work as listeners or readers or viewers is up-ended and we’re given something we didn’t know we were waiting for until we felt it there, shocking and wonderful.

It set me thinking about my own ongoing dialogue with perfectionism. Most of us who practice the arts train for years to refine and polish and contain our outbursts, channeling them through words or color or sound or movement. It’s a huge discipline, and if the effort is genuine and well-directed, we do arrive at a level of competence that allows for beautiful gestures that are intentional rather than accidental.

Still, in this increasingly mediated world where we can edit photographs and design documents on our laptops, I sometimes wonder if we are seduced by a kind of perfection that is characteristic of machines rather than humans. Machines can do a lot of things, but they can’t think for themselves and they can’t respond—think of the last time a recorded voice called to sell you a cruise or a credit card with a lower interest rate.

Listening to a great jazz musician is a lesson in balancing the desire for machine-like precision with a commitment to human expression and its almost unfathomable range of emotion, inflection, intention. To catch that range, both artists and their audiences have to welcome shifts that are startling and sudden and spontaneous. Those moments are where the wonder lives.

The French critic Roland Barthes celebrated what he called “the grain of the voice,” a certain quality in writing and other art forms that is distinctive and memorable and absolutely particular. When you can feel the specific character of a voice, you know an actual person has offered you something, and that you’ve found a way to receive it.

Jimmy and the rest of the band offered us the grain of their voices, a quality that is raw and personal and undeniably real. They offered it with generosity, and gave each of us in that crowded room a chance to feel just a little more hooked into this human family.