And in all of this, there is no voice that articulates the dangers potentially present, no leadership that has the reach of the globe that inspires. That Mr. Putin should be, even in a negative sense, the “strongest” leader on the scene, the one with a thought-out, calculated agenda, is a deep sadness.

The West has had some peace since the last great war, almost 70 years of it now. And we have had with that peace an astounding march of technological and material progress. Both tend to make people forgetful of worse times. It renders them careless of the foundations upon which peace is first secured and then maintained, and nourishes the delusion they are exempt from the horrors and perils that have been a constant in human affairs.

So it seems now to some, as it seemed to some a century ago, that there is a menacing scattering of events and conflicts, where a disturbance, an accident or misadventure (such as the shooting down of the passenger jet) in one arena could unwind into a chain of unforeseen events, a haphazard flow of unpredictable cause and effect. And here, despite Eliot’s cautions, we can draw another clear and unconfused message from history: Whenever full-scale war comes. it is always worse than the previous one. Not even the trenches of the First World War, or the terrible technologies of the Second, will carry the freight of conflict in our time. We, after all, as we like to say, have “mastered” the atom.