Teacher: The One Who Made the Difference

In 1969, Mark Edmundson was a typical high school senior in working-class Medford, Massachusetts. He loved football, disdained schoolwork, and seemed headed for a factory job in his hometown—until a maverick philosophy teacher turned his life around.

When Frank Lears, a small, nervous man wearing a moth-eaten suit, arrived at Medford fresh from Harvard University, his students pegged him as an easy target. Lears was unfazed by their spitballs and classroom antics. He shook things up, trading...