It was the time of unraveling. Long afterward, in the ruins, people asked: How could it happen?

It was a time of beheadings. With a left-handed sawing motion, against a desert backdrop, in bright sunlight, a Muslim with a British accent cut off the heads of two American journalists and a British aid worker. The jihadi seemed comfortable in his work, unhurried. His victims were broken. Terror is theater. Burning skyscrapers, severed heads: The terrorist takes movie images of unbearable lightness and gives them weight enough to embed themselves in the psyche.

It was a time of aggression. The leader of the largest nation on earth pronounced his country encircled, even humiliated. He annexed part of a neighboring country, the first such act in Europe since 1945, and stirred up a war on further land he coveted. His surrogates shot down a civilian passenger plane. The victims, many of them Europeans, were left to rot in the sun for days. He denied any part in the violence, like a puppeteer denying that his puppets’ movements have any connection to his. He invoked the law the better to trample on it. He invoked history the better to turn it into farce. He reminded humankind that the idiom fascism knows best is untruth so grotesque it begets unreason.

It was a time of breakup. The most successful union in history, forged on an island in the North Sea in 1707, headed toward possible dissolution — not because it had failed (refugees from across the seas still clamored to get into it), nor even because of new hatreds between its peoples. The northernmost citizens were bored. They were disgruntled. They were irked, in some insidious way, by the south and its moneyed capital, an emblem to them of globalization and inequality. They imagined they had to control their National Health Service in order to save it even though they already controlled it through devolution and might well have less money for its preservation (not that it was threatened in the first place) as an independent state. The fact that the currency, the debt, the revenue, the defense, the solvency and the European Union membership of such a newborn state were all in doubt did not appear to weigh much on a decision driven by emotion, by urges, by a longing to be heard in the modern cacophony — and to heck with the day after. If all else failed, oil would come to the rescue (unless somebody else owned it or it just ran out).

It was a time of weakness. The most powerful nation on earth was tired of far-flung wars, its will and treasury depleted by absence of victory. An ungrateful world could damn well police itself. The nation had bridges to build and education systems to fix. Civil wars between Arabs could fester. Enemies might even kill other enemies, a low-cost gain. Middle Eastern borders could fade; they were artificial colonial lines on a map. Shiite could battle Sunni, and Sunni Shiite, there was no stopping them. Like Europe’s decades-long religious wars, these wars had to run their course. The nation’s leader mockingly derided his own “wan, diffident, professorial” approach to the world, implying he was none of these things, even if he gave that appearance. He set objectives for which he had no plan. He made commitments he did not keep. In the way of the world these things were noticed. Enemies probed. Allies were neglected, until they were needed to face the decapitators who talked of a Caliphate and called themselves a state. Words like “strength” and “resolve” returned to the leader’s vocabulary. But the world was already adrift, unmoored by the retreat of its ordering power. The rule book had been ripped up.