The effect and essence of terror lie in the randomness with which it makes people victims. Why must an eight-year-old boy — waiting to take his father in his arms after a successful run at the finish line of the Boston Marathon — die? Why do others, who gave their best on the stretch, end up as cripples? Why do spectators who wanted to be inspired by high athletic performances lay in their own blood? Because the horrible message is: It can strike anyone.

Whoever ignited the bombs in the middle of hundreds of thousands of fitness fans in the heart of Boston had just that in mind: a perverse statement of perceived power that all draw upon — individual perpetrators, national as well as international networks. It is always a single, last emotion that drives them: hate. The Breiviks, the bin Ladens of this world may have different motives, but the method they choose remains the same: the spreading of chaos and death.

It is good that America, the country that was overspread with a great number of grave terror attacks in the past decades, even in the shock of Boston, held back from premature accusations of guilt. Not just the president reacted calmly. Namely, the variety of enemies that threaten their freedom also counts among the sorrowful experiences of U.S. citizens radical Islamists from abroad and anti-government fanatics in the interior. It is necessary to keep both in view.

Terror kills indiscriminately. It is never random. It will always hit at the point where our open societies are most vulnerable. It can only be countered by one thing: persistence in combating it decisively. In a way it requires the endurance of a marathon runner who approaches the task with determination. That is the message that should come from Boston.