Two families of the German high bourgeoisie, circa 1900--the Kempowskis of Rostock, the deBonsacs of Hamburg--illustrate those ""days of greatness"" when commerce and nationalism and well-being and religion all blended into a smug patriotic soufflÃ‰ which was doomed to fall. . . a fall from which Germany never recovered. Kempowski's two clans of burghers are similar but not identical: the Kempowskis of Rostock, led by father Robert William (but actually by Anna, the more impetuous mother), make their money from a ships-brokerage business. Fine food, artistic salons, illnesses of indulgence (syphilis, transmitted by Anna to Robert William), and a general surfeit of creature comforts--all these mark the surroundings in which daughter Silbi and son Karl are raised. Meanwhile, the Huguenot Protestant deBonsacs, in Hamburg, are manufacturers and live no less well--but with a religious rectitude, a pious self-regard, and a frugality that demonstrate the other side of the coin of Germany's turn-of-the-century placidity and invulnerability. Then, when the deBonsac daughter, Grete, meets young Karl Kempowski in Graad, on the Baltic, where both families arc coincidentally vacationing in 1915, the sagas braid--to be loosened shortly thereafter (as was Germany itself) by war: Karl is made a junior officer, originally full of zest, but hi the end battered by defeat and surrender. German author Kempowski lays in this story tile by tile, small scenic sections that resemble not so much still photos of time and place and testimony as snippets of what feel like silent movies. But though there's a steady sense of verisimilitude here, the book seems longer than it is--more a weightily dramatized social-history lesson than full-fledged fiction, and only a pale reflection of the novel with which it inevitably invites comparison: Mann's Buddenbrooks.