HISTORIANS GOT THEIR instructions early. In the second century B.C. the Roman historian Polybius issued these orders: “Directly a man assumes the moral attitude of an historian he ought to forget all considerations, such as the love of one’s friends, hatred of one’s enemies. … He must sometimes praise enemies and blame friends … if you take the truth from History, what is left is but an improfitable tale.” He stated the historian’s duty clearly and forcefully and then lived long enough, until he died at the age of eighty-two in a fall from his horse, to see that in ancient Rome his rule often was ignored.

How much of the rigor demanded of the modern historian applies, or should apply, to the journalist? All of it, I would say. But how much of it actually does? How much of it can be?

Historians and journalists are not often found in the same family, though both occasionally have been found in the same person (Bruce Catton, Allan Nevins), but both are found in my own family. I have been a journalist for forty years, long enough to take pride in seeing my son grow up to teach history at Harvard. Hence these few thoughts about the differences between his work and mine.

What are the differences?

The most obvious is that the journalist deals with the triumphs and follies of the human race and with the behavior of the natural world every day and is not always allowed the time to reflect on them, to consider what they will mean, if anything, when the acid-filled newsprint of today’s newspaper has begun to yellow and crumble and when the electromagnetic vibrations of tonight’s news broadcast have forever disappeared somewhere into the ether. He deals with events he knows absolutely will have no significance beyond the next edition or next broadcast, as when every week or so a truck piles up on some highway and commuter traffic is delayed by tons of molasses or cantaloupes strewn on the road. But on other days, in my own experience, there were events that started as journalism and ended as history—when wars started, wars ended, Presidents were murdered or forced to resign, when atomic bombs were dropped on Hiroshima and Nagasaki.

None of us who wrote, printed, and broadcast the news from Hiroshima that day had any idea of what we were doing, not for any lack of professional rigor or any lack of professional pride, but purely and simply because of the absence of full information due to the U.S. military’s censorship restrictions and refusal to answer questions, because few of us were knowledgeable in nuclear physics, and, above all, simply for lack of time. The next edition or the next broadcast never is more than hours away. We knew it was a new and complex