ON THE 11th anniversary of 9/11, fanatics reminded the world that life is fragile and that, in Secretary of State Hillary Clinton's perhaps overmeasured words, the world is still "a confounding place."

An attack on the U.S. Consulate in Benghazi, Libya, killed four Americans, including Ambassador Chris Stevens, who was working tirelessly to bring democracy to that country. In Cairo a mob scaled the walls of the American Embassy, tore down the U.S. flag, and replaced it with a black Islamist flag.

Ambassador Stevens, a 21-year State Department veteran, was in the midst of a "noble and necessary mission," noted Mrs. Clinton, helping Libya become a normal country after decades of rule by a despotic regime. Tuesday's slaughter was the first time in 32 years that an American ambassador lost his life in service to the nation.

Terrorists may have used the mobs rioting in Libya and Egypt over a 17-minute YouTube clip as a diversion. The film, which slammed Mohammed, was created by an Israeli-American from California. No doubt the protesters were angered--as Christians, Jews, and adherents of virtually every other religion have been on occasion by blasphemers.

But being offended is no justification for murder. Not in a civilized world, anyway--which is what Ambassador Stevens was working toward in the violence-laden Middle East.