The world, in all its tangled webs, will be read into the Boston bombing suspects.
For some, the Tsarnaev brothers are Chechen avengers, young men seared by the long war in Russia's "southern backyard."
For Vladimir Putin and his regime, this deed of terror in an American city is, doubtless, a vindication of the iron fist with which the Russians fought their long war against Chechnya, proof of the malignancy of the Islamist menace.
Foes of immigration can be expected to offer the Tsarnaev brothers as evidence that a nation that throws its gates wide open courts this kind of calamity.
One way or the other, the matter of Islamist radicalism hovers over this episode.
There are other testimonies that speak to the puzzlement of our time, to the difficulty of drawing hard lines between cultures in conflict.
A classmate who knew Dzhokar, the younger of the two brothers, from Cambridge Rindge and Latin School described him as a cool guy, a regular American kid on the wrestling team.
Another classmate, Ty Barros, describes a boy who liked sports and listened to rap music and hung out with other kids in the neighborhood. Dzhokar never discussed religion and politics, this acquaintance adds.
Pamela Rolon, a residential adviser in the dorm where Dzhokar lived at University of Massachusetts at Dartmouth said that the young man "studied hard and spoke English beautifully."
The world outwits us, furrows run across it: We look for fixed identities and whole, intact worlds, and we find instead the shaking up of continents, the intermingling of peoples and ways.
For me, the earliest evidence of the foreign birth of the bombers was not their features, as we saw them in the grainy early footage, but the baseball caps - one turned backward - and the backpacks.
This was Americanism as the two assailants understood it - easily available, the kind that could slip across boundaries, evade detection. American urban culture fashioned the look, but it is now the property of one and all.
We know the pattern. These assailants live on the seam between countries and cultures.
Think of Faisal Shahzad, the young Pakistani who, three years ago, sought to detonate a car bomb in Times Square.
He had driven his car from his home in Bridgeport, Conn. He had worked for Elizabeth Arden, and completed that all-American degree, the MBA. Neighbors recall him jogging in the evening near his home.