I’m ditching class to join the throng of Bostonians collectively fleeing their wintry cocoons to embrace the first signs of spring. As I pass tired joggers resting on park benches and young couples sunbathing on brown and green patches of lawn, I notice a man wearing a gray fisherman’s hat sitting in a motorized wheelchair. He’s parked on the edge of the Boston Common--a frozen spectacle among a frenzy of moving bodies…