Evil. Its ugly face showed itself anew yesterday as two bombs exploded on Boylston Street near the finish line of the Boston Marathon. The images were searing, the first blast followed by billowing smoke and a runner falling to the ground, then another burst of smoke down the street, people running frantically, the screaming, the sirens, the confusion, the blood on the street. Then, the news: two people are dead. Then, the worse news: one of the two was an eight year old boy. Then, still worse news: a third person had died and more than a dozen were still in critical condition.