I had a teacher once who called his students "idiots" when they screwed up. He was our orchestra conductor, a fierce Ukrainian immigrant named Jerry Kupchynsky, and when someone played out of tune, he would stop the entire group to yell, "Who eez deaf in first violins!?" He made us rehearse until our fingers almost bled. He corrected our wayward hands and arms by poking at us with a pencil.

Today, he'd be fired. But when he died a few years ago, he was celebrated: Forty years' worth of former students and...