John of Gaunt (1340-99), like many premodern historical figures, poses a problem for the contemporary biographer. Norman Cantor’s subject, the founder of the Lancastrian line, the richest man in Europe, a devotee of courtly love, and an enthusiastic champion of the chivalric tradition, left behind 500 pages of business correspondence but not one personal letter.What can a biographer do?

Actually, as Mr. Cantor demonstrates,a good deal.Like generations of biographers before him, Mr. Cantor situates Gaunt in his age, devoting chapters to “Old Europe,” “The Great Families,” “Women,” “Warriors,” “The Church,” and “Politics.” Mr. Cantor calls his approach “sociological biography,” by which he means we can fathom Gaunt by acquiring a solid understanding of his world.

This was a world of elites – primarily the members of great families, the Church, and the monarchy – that is not so different, the biographer suggests,

from our own. Thus Mr. Cantor observes: “Like the American billionaires of today, members of the high aristocracy exercised power and influence beyond their wealth and specific political connections.” Elites set the style, the fashion, and the governing ideas of an age, the biographer goes on to explain.

Judged in academic terms, Mr. Cantor’s book is old-fashioned history – advancing almost a “great man” theory of history, given his book’s title, “The Last Knight.” And from the contemporary historian’s point of view, too much perhaps is made of Gaunt himself, since even in his lifetime the shift from the Middle Ages to the Renaissance could be detected: in Chaucer’s psychological realism, in the peasant revolts against Gaunt himself (a stern landlord), and in the beliefs of religious dissenters like John Wycliffe (1330?-84), who presaged the Protestant Reformation. Not long after Gaunt’s death, England would be torn apart by the War of the Roses.

But even as he was the representative of a dying age, Gaunt was a herald of the new. He sponsored Chaucer, for example, though the biographer believes that Gaunt’s later reduction of the poet’s subsidy reflected a waning enthusiasm for his protege’s satirical portrait of Church and society – not to mention Chaucer’s obvious relish for non-aristocratic characters. Similarly, Gaunt backed Wycliffe, then backed off when the radical preacher directly assaulted Roman Catholicism. In Mr. Cantor’s view, he could never have been comfortable as a Renaissance man.

Gaunt certainly did not want to change the structure of society. The peasant revolts did nothing to alter his manner of governance. Although he had a claim to the throne, he loyally propped up Richard II, a weak king, who would be swiftly unseated by Henry IV, Gaunt’s son, shortly after Gaunt’s death. He was happiest as a warrior and a lover, wasting a good deal of wealth on futile wars in France and in Spain and pursuing his claim to the throne of Castile.

In his later years, Gaunt sensibly withdrew from military adventures and took as his third wife Catherine Swynford, his mistress and a commoner.This unprecedented act outraged Europe’s aristocracy, and it transfixes his biographer: “Gaunt was a passionate man, and women meant a great deal to him,” Mr. Cantor writes, just after a passage in which he imagines what Gaunt would have written in a personal letter:

My beloved Cate: I hope you

received the wood from my estates, the two barrels of Bordeaux claret, and the pearl necklace from Egypt that I sent you. It

is not four years since I first saw you in the Nursery taking care of my two daughters. I was immediately struck by your beauty and the fine figure of a woman you represented. I admired your breasts in particular. Constance, the Spanish wife [Gaunt’s second wife] smelling of garlic and olive oil, was still alive. But the first time I saw you, I knew I had found the woman to replace my late lamented Blanche. The first time I slept with you I knew you would be the great love of my later years. Now that you are pregnant with our child, our love will be long-enduring. Take good care of yourself, Lancaster.

This is an extraordinary performance for a biographer – and much more satisfying than the “must have been” formulations usually resorted to when facts are not ascertainable. Every sentence in this passage is steeped in Mr. Cantor’s understanding of the courtly love tradition and in the aristocrat’s manner of address. I would liken it to those passages in Faulkner where the characters suddenly stop speculating on the past and are there – if only for a moment. In such cases, the past is more palpable precisely because it is so evanescent. The other stunning part of this en grossing biography is the last chapter. Mr. Cantor points out that historians will have to return to the study of elites, after having been seduced by the chimera of socialism and the Annales school of French historians, who argue that history is made from the ground up by the peasants and the working class. R.H. Tawney and generations of Marxist historians sidetracked our understanding of the way the modern world developed, Mr. Cantor argues.

As a “more realistic and balanced historical view takes hold,” Mr. Cantor concludes, “people from the past, like John of Gaunt, will attract closer scrutiny and receive deeper sympathy.” I have to confess that while reading Mr. Cantor I certainly developed a soft spot for Gaunt, especially after learning we share a common ancestor,Rollo,”a heathen Scandinavian chieftain,” who in 911 “seized a piece of the faltering Carolingian empire in Northern France,” and whose successors made it over to England in 1066.