Published first in 1957, the year of Giuseppe di Lampedusa's death! That was only six years before the acclaimed film by Luchino Visconti was released. But Il Gattopardo is ineluctably a 20th C novel masquerading as a 19th C Romance, in style as much as in setting. I insist on telling you this because, if you didn't read the preface or look at the back of the title page, you might well be dangerously startled when Lampedusa first breaks the frame and refers to events of his own lifetime. That doesn't happen until a third of the book is finished; until then there is no 'narrator' in sight. Thereafter, however, Lampedusa inserts his "I" at judicious intervals, calling the reader away from the Sicily of the 1860s with metaphors of modernity. Eventually he even mentions the atomic bomb.
Possibly some readers will be annoyed by Lampedusa's occasional first-person anachronism, but I don't think they were an accident or an error of style. They're a significant clue as to the intention of the novel, which isn't simple nostalgia. Lampedusa doesn't whitewash his setting or his characters; Sicily in the 1860s was a land of grievous poverty and economic stagnation, a society still bogged in feudalism, and the aristocratic families that supply nearly all the characters in Il Gattopardo were decadent, besotted with themselves and their possessions, reactionary, indifferent to the misery of their society. Their highest aspiration was to hang on to their luxury and privilege as long as they could, at least their own lifetimes, and let the next generation fend for itself. Only the central figure, Prince Fabrizio Salina, gets much respect from his 'creator' Lampedusa. His flaws and follies are the same as any other of his class, but his vitality and his inward perceptions of his milieu exalt him above the stagnant morass of his insular society. It's not mere words, on Lampedusa's part, to depict the Prince's fascination with astronomy. Salina is, for this author who might be his great-grandson, as genuine a hero as historical reality allows.
The plot of Il Gattopardo is rather loose. It's the era of the Risorgimento, the unification of Italy with Garibaldi as the charismatic revolutionary. Prince Salina imagines himself, correctly as it turns out, as "above the fray". His preeminence will remain untouchable and his Sicily, with all its failures and inequities, will remain eternally the same. His wealth is being eroded by energetic and unscrupulous lower-class parvenus, but he disdains to resist them; such has always been the case, a process of revitalization. The Prince's nephew, a charming and talented fellow whom we see only as the Prince sees him, is an enthusiastic Garibaldino and an avatar of the Sicily-to-be, but his uncle's affection for him is stronger than any political discord. Eventually a love story unfolds, between the nephew and the beautiful daughter of the Prince's polar opposite, the up-and-coming parvenu "Don" Calogero. That romance is in effect the structure of the novel, but the heart and soul of Lampedusa's tale is the complex depiction of the personhood of Fabrizio Salina.
If it's not nostalgia, then what is it? I think it's a celebration of "tempo perso" -- temps perdus/lost times -- a monument of their beauty as well as their infamy, intended to rescue them from oblivion. In that mode, it reminds me of the extraordinary Squarcialupi Codex of 15th Century Florence, an opulent illuminated volume containing the best music of Tuscany's distinctive indigenous composers, whose style was already utterly out of fashion, displaced by the arrival of the Franco-Flemish polyphonists in Italy. The redactors of the Squarcialupi Codex had no expectation of reviving the music of their greatest native composers like Francesco Landini, nor even to encourage performance of it. They meant forthrightly to immortalize the accomplishment by wrapping it sumptuously in museum shrouds. Il Gattopardo strikes me as having the same intention, not to replay the 'music' of pre-modern Sicily but actually to inscribe it in the museum of literature before its image faded from human memory.