Jonathan Zimmerman: Boston Marathon, Long a Melting Pot for Good

Jonathan Zimmerman, author of "Small Wonder: The Little Red Schoolhouse in History and Memory," is a professor of history and education at New York University.

A Chinese graduate student, killed by one of the explosions. An immigrant from Costa Rica, clad in a cowboy hat and assisting a victim who lost his legs. An Indian-American surgeon, charging toward the injured after completing the race himself.

And two Chechen brothers, suspected of causing all of this mayhem.

These images have haunted and inspired us since last Monday's bombings at the Boston Marathon. Lu Lingzi was studying statistics at Boston College. Carlos Arrendondo, who was handing out flags at the race, lost a son in Iraq. Dr. Vivek Shah is an orthopedic surgeon at New England Baptist Hospital, where he returned to work just a day after bandaging several of his fellow runners....