Most of all, the marathon bombing should not mean that we stop running races or stop coming out to cheer. Should we tighten security? Of course, but where do we really find security? It can't be in merely building more walls between us and investing in thousands more closed-circuit cameras. We will not be saved by shrinking into safe rooms or scapegoating people of another faith. Especially when the bombers have come from those living among us, being "tough" could mean each of us turning against all others, treating everyone we meet as a potential enemy. We should remember, to our great shame, that we tried that immediately after Pearl Harbor, imprisoning those with a Japanese surname, regardless of their history, personality or patriotism.