Why Old Men Are Mad : THE ORIENT EXPRESS, <i> By Gregor von Rezzori (Alfred A. Knopf: $21; 208 pp.)</i>

Not so very long ago, in the vast land stretching magically from the Bukovina to the Inn and from Galicia to Bosnia-Herzegovina, lived in relative peace and prosperity a population of many tongues, creeds and hatreds, watched over by an aged two-headed eagle. Then came the Great War. By the time its travail ended, new states--some with newfangled names--had sprung up as though from dragon seed.

At their freshly traced borders, passengers lolling in luxury on the Orient Express, as it thundered from the Golden Horn to London, were for the first time obliged to present passports and visas. Even so, until the next world war, this space, though subdivided, remained spiritually united as what it had always been: the great melting pot of Europe, perhaps the richest source of genius and invention since Attic Greece.

A “mother’s boy, half-English, filthy rich Armenian father, importer of God knows what (Anatolian hazelnuts, Siberian silver foxes, Italian speedboat motors and Czech canons), ‘a boy with ready money,’ as the Romanian vernacular put it . . .” in the ‘30s would take that train or one just like it from Braila, “near the mosquito-veiled Danube delta on the Black Sea,” to his elegant British boarding school.

Fifty years later, we meet him again, as the narrator of Gregor von Rezzori’s tender, sardonic and heart-rending “The Orient Express.” Now in his mid-’60s, he has once more boarded the Orient Express, recently revived and refurbished amid modern tourist-industry hoopla to provide a retro thrill for a motley public of retirees and, of course, travel agents on no-expense promotion junkets. It may be the narrator’s last voyage.

The narrator’s name is Aram; like his father he is filthy rich, “ornery” in business, and dark like an Oriental prince or a Jew. He is often mistaken for the latter. Since the Second World War he has lived in New York and, one supposes, has remade his fortune by his own efforts. Fate deals strange cards to displaced persons: Aram’s wife, though blonde, is a Jewish American Princess, exquisitely beautiful, frigid and possessed of long legs and a vulture-like mother with a sharp eye for contemporary art.

The Princess is called Linda. That must have been the fashion the year she was born; after all, Juanita or Ingrid would have done just as well. The mother, the art and Linda’s milieu of scruffy journalists all are equally repugnant to Aram. He has “dabbles.” One “dabble,” of fairly long duration, is with a displaced person of another sort: a preposterously sentimental, plump, French beautician, a “nanny hand” expert at enabling an elderly gent to maintain the high level of sexual performance that the last 50 years have accustomed him to consider a duty as well as a pleasure.

It could have been otherwise. Had Aram married a properly elegant WASP, or one of the countless European maidens of “good family” so widely available in Manhattan, he would have had his huge spread on the Upper East Side and the house in Southampton. On the other hand, he might have been spared the irritation of Linda’s middle-American decorating sprees, and the indignity of tight jeans studded with metal, cowboy boots and lumberman jackets which, feeling declasse and hating every minute of it, he sports on weekends, presumably because it is the garb of Linda’s guests. Instead, depending on the season, he would have been swathed, like all minor shipowners and Levantine millionaires beached in the Hamptons, in linen, raw silk or cashmere.

Aram has a guilty secret. It is the loyalty and softness of his heart. He truly loves his Linda. As he is a gentleman, he hates himself for being ashamed of the beautician, particularly when she is at her most offensively vulgar. But, he also has a hot temper. One day, in high dudgeon, he leaves for Lord knows where, determined to get as far away from these women as his inexhaustible credit cards and long-repressed wanderlust will carry him.

Hawaii, Tokyo, Vienna--we catch up with him in Venice. He is alone, staying in a hostelry whose grating luxury is reminiscent of the charms of the Cipriani. The window of his room looks out on a hedge of neatly trimmed shrubbery. Mercifully, it conceals the clientele gathered around the pool, on which Aram could provide details, with embarrassing precision. He could imagine the men out there down to their very hemorrhoids and prostate swellings, the women to their conscientiously checked ovaries.

Of course, by this time he has measured the disconnection between his memories--good and bad--of the Europe he knew as a boy or young man, and the succession of theme parks, not all made by Walt Disney, which are his present surroundings. His horror and disgust are nearly total.

Nevertheless, in part because he knows that he too has turned into a visitor in the theme park called “the Old World,” he decides, as though on a dare, to plunge into the ultimate kitsch promised by the brochure of the Compagnie Internationale des Wagon-Lits. Venice to London on the Orient Express! One evening, one night and one day of memory and inexpressible suffering, and von Rezzori’s high-wire act succeeds: Improbably and nobly, Aram has made peace with himself. He has come to understand why old men are mad.