There is one book that says it all.


An old book, nearly a classic. Oddly, it is rarely mentioned in France.


This book, published in 1957, is titled The King's Two Bodies: A Study in Mediaeval Political Theology.


Its author is Ernst H. Kantorowicz, a Jewish historian and medievalist from Germany who immigrated to the United States in 1939.


If I could give only one piece of advice to French President Nicolas Sarkozy, and to those around him who are concerned about his image, and in particular the perception of his presidency--which has been greatly damaged not only by an economic downturn, but also by his autocratic style, his recent divorce, his whirlwind romance with ex-model Carla Bruni--it would be to drop everything and consult this great book, this masterpiece about the history of the Middle Ages and contemporary political science.


What exactly is Kantorowicz's thesis? Broadly speaking, it is that a sovereign or ruler does not have one body but two.


More precisely, it is that at the exact moment a man attains political office, his person, his being, literally splits in two.


He has an ordinary body, which Kantorowicz calls "profane." It has all the desires of the human body, its aggravations and passions.


And then he also has a sacred body, quite detached from the scheming of the profane body, as impassive as the other is passionate, as silent as the other is loquacious and temperamental. If not mystical, it is at least mysterious, immaterial, invisible.


The theory suggests that the exercise of power and prestige is related to the struggle between the "vulgar" and the "ethereal" bodies, between the perishable and the sublime. The proportions may vary, but there must be balance; coexistence is a non-negotiable principle.


When Sarkozy's situation is examined through this prism, his case is quite simple: Too much of the profane body and not enough of the sacred. The profane body is in fact dominant, taking over, swallowing up the sacred one.


Somehow, in his romance, his penchant for jogging, his displays of impatience, there is too much flesh, an overexposure of ordinary passions and pleasures, something never before seen in other presidential administrations: an unexpected eclipsing of the sacred body, which does not experience pleasure or passion, and demands both distance and respect.


Unlike some of his other adversaries, I look upon the president with a fair amount of sympathy.


The problem is not his private life--Francois Mitterrand certainly had his secrets, which he later revealed rather ostentatiously.


It is also not the coarseness of his recent imbroglio at the agricultural fair in Paris when he shot back, "Get lost, you jerk," to a man who had insulted him. Is that really more shocking than Jacques Chirac's outburst at Israeli security during his visit to Jerusalem's Old City in 1996, or the rather inappropriate "chienlit" expression used by Charles de Gaulle in May 1968?


It isn't even that he's too present, too directly involved in day-to-day policy--is it not for this, and for his boundless energy, that the French electorate chose him?


No. The real problem--which the public perceives and does not excuse--is that he has seemingly tossed aside the sacred body and the modern doctrines of the Machiavellian prince. The real problem, which is chipping away at Sarkozy's popularity in the polls, and which will soon hamper his ability to effect change, is that this man, so attentive, perhaps too attentive, to France's "Christian roots," has in this matter crossed the line toward full and complete secularity.


The presence of the sacred body was palpable with Chirac, Mitterrand, de Gaulle, Bill Clinton, and now, even with poor, hopeless George W. Bush; its aura could be felt despite the vulgarities they committed. But we don't see any trace of it in the young French president, and that is tragic.


Perhaps he thinks he can bring it all back with a clear, lucid strategy.


Perhaps he thinks he is breaking with tradition, generating a new image of the sovereign.


And perhaps he thinks that in so doing, he is way ahead of the commentators he scorns, who are stuck in the past. Does he think "he who laughs last, laughs best"?


If this is the case, Sarkozy is making a mistake.


Even if he tries to re-create the presidency, wipe the slate clean and begin again, he is governed by the same rules as all politicians. The theory of Kantorowicz is not a hypothesis but a theorem, and theorems, by definition, have no exceptions.

French philosopher and writer Bernard-Henri Lévy is the author, most recently, of American Vertigo: Traveling America in the Footsteps of Tocqueville and Ce Grand Cadavre a la Renverse. Translated from the French by Sara Sugihara.