Intellectual batting practice: A question on Hitler lobs through the venerable gloom of the Founders Room at the Folger Library. Why, Professor Plumb, does Hitler continue to eke such fascination?

First, a brief ballooning of air into the left cheek; then a gathering of face into friendly frown under hornrimmed glasses, and J.H. Plumb, master of Christ's College, Cambridge, raps it neatly into the outfield: the trauma of the war and all, much like the Trojan war of course, but, too...

"Hitler was very amusing, a very funny speaker," he says in the sort of British accent with which one could both talk and bite a flake of skin off the lower lip at the same time.

"He didn't capture the support of the German people with just ranting," he says, instantly rendering that thought unthinkable within the effective radius of one of the earlier atom bombs.

"We keep re-evoking the horror of the Nazis, or we sweep it all under the rug. What we should be doing is trying to analyze how this happened."

And, as he will point out in a few minutes, America has to stop dwelling on its defeat in Vietnam and come to understand that world power, in history, means losing a few, now and then.

British historians are like Texas oilmen or Canadian lumberjacks -- a benevolent stereotype, even an evolutionary fillip, as if a gene went happily awry sometime around the time of the Venerable Bede, and keeps cropping up in the form of a Trevor-Roper or an A.J.P. Taylor or a Plumb.

"Being a British historian is not a disreputable occupation," Plumb concedes, nestled in an armchair beneath linen-fold paneling and a unicorn tapestry. "But the best ones are French, of course, not British. All the new insights, all the new fields are found first by the French."

Someone confesses he con't name a single French historian.

"Braudel? You don't know Braudel? It was Braudel who invented the wonder phrase, the long duree -- the English keep chopping history up into small bits, you see."

Well, there's Toynbee, of course -- but scarcely has the name been mentioned before Plumb's heels are dug in.

"It's so marvelous when Toynbee calls the 17th century a period of peace -- he has to, you see, to fit his theory. But there were only two years when there wasn't a war, the 30 Years' War and so on."

In fact, he once got two of the longduree boys at one blow, when, commenting on Oswald "Decline of the West" Spengler's style, he wrote:

"As well as infelicities, there were, of course, monstrous howlers of the type that we have grown more used to since Toynbee became a historical prophet; at least it is charitable to call them howlers."

Which historian does that last phrase refer to?

"Both," Plumb says with a small smile.

Then again, Plumb -- like most British scholars -- lacks the unconditionalsurrender venom of American intellectuals when they get to scrapping.

"Yes, there are some American historians who can't be put in the same room with each other," he says. "But I suppose the biggest feud we have is between trevor-Roper and Taylor, and they meet on perfectly good terms -- though they probably wouldn't support each other for jobs, a bit of sub rosa on the letter of recommendation, no doubt...

"But we're all clubmen together, we meet each other so much more, so we can't be as nasty as you can when you only see each other once a year at a convention."

Plumb is here to deliver the Folger's annual Mellon lecture. His topic is "The Acceptance of Modernity in Eighteenth-Century England," a title which might seem contradictory here, but never in England.

Plumb, for instance, specializes in modern English history, the definition of which "depends on where you are. The Regius Chair of Modern History at Oxford refers to all history after the decline of the Roman Empire. But most would say modern history starts after the Reformation or Renaissance," Plumb says, pronouncing it re-NAY-sance in the English style.

His own durees have been successful both long and short. One book is entitled simply "England in the 18th Century." At the same time, he can list what George IV ate for breakfast, six weeks before he died:

"Two pigeons, a steak, a bottle of Moselle, a glass or two of port, a glass of brandy, and then, because he suffered terrible stomach pains, a little laudanum."

He has written on the porcelain madness of the 18th century, and on the changing concept of children, of which he has none.

"Saved me a great deal of sadness, no doubt. I've always seen childhood as a sickness, a deformity. I hated it, hated being a child. Even when I was 21 I wanted to be 28." It's unsetting to imagine this bald-headed man of 67 as a child -- inkstained? refractory? -- though he says that 40 would be nice for an indefinite visit.

The youth he worries about now is America's.

"You've only been a world power for a relatively short time -- in a massive way since World War II. It's high time America got more self-confidence -- nerve! It's too full of self-doubt. No country has ever given so much away."

It is pointed out that no American can politely make this point in Europe, especially France.

"Yes. Better if I say it, isn't it? And the French -- they've been doing that for a millennium now. I like the French, you understand..." But one presently notes on his face the tart delight only an Englishman can take in pronouncing the word "frog." Then he's off again, chastising America for being ungrateful to the French -- "You couldn't have won the revolution without them, but it's always bite the hand that feeds you. Human nature, I suppose."

Anyhow, the problem is that "public figures have so little history," he says. "You lost in Vietnam. Every country loses wars. Being a world power means lots of disasters, minor defeats, lots of resentment. You've got to learn that."

It seems appropriate, especially given the fine tang of iconoclasm which hangs in the air, to point out that America might have had less stubborn pride to lose in Indochina had we admitted that we lost the War of 1812, that the very spot on which Plumb is sitting may well have been in British flames.

"That wasn't a war," Plumb retorts. "That was an incursion."

Clearly, though, a spark still burns -- enough to warm the hands by, at least.