The windowless room is dark except for static sputtering on a video monitor. Beside the monitor, on one of the stackable chairs, sits Jim, a gaunt young man who stares at his knees and pounds them again and again with his fists. His assault is as unrelenting as the static. That must be the point, I think, but my conviction quickly fades. I shift in my seat and look around to see if anybody appears to understand what’s happening. Postures of contemplation emerge from the gloom: chins propped on hands, jaws grinding gum. Several students lean forward, mesmerized by the granulated light and the steady thwacks of impact.

The year is 1973, and our instructor, the conceptual artist John Baldessari, stands in a corner. Six foot seven, with shaggy white hair and beard, he wears an expression that is, as always, inscrutable, his hands buried in the pockets of his jeans. He knows that the aesthetic value of any object or activity cannot be measured hastily; the history of the avant-garde is the history of critics who rushed to judgment, whom time proved foolish. Here at the California Institute of the Arts, we must inch toward, rather than jump to, conclusions.

Jim continues to pummel himself and no one speaks. Words would be brutish and premature. And so we stare in a kind of numb reverence until a secretary from Admissions barrels into the dark room to deliver a phone message. She squints against the gloom and plunks herself into a chair beside Jim, holding out a folded note. “Your mother wants…”

He shushes her, punishes his knees.

She straightens her skirt and waits a moment. “Jim,” she says, “I haven’t got all day. Your mother wants you to…”

His fists stop midair, and he looks up from his lap. “I’m doing a performance,” he hisses. Just as the secretary turns and finally sees a roomful of students staring back at her, Jim lurches to his feet and hits the monitor’s off switch. Static evaporates. “Your mother,” she continues in ...