Very occasionally there appear movies so epic in their demands that we don't watch them so much as vanish into them. We set aside our own lives for a day or two or five, luxuriating in other people's dramas, learning to breathe in different rhythms, returning slightly changed. European filmmakers do this particularly well, as anyone who has made it through the 16 hours of ''Berlin Alexanderplatz" (1980) or ''Heimat" (1984) knows, but using DVD to gorge on a ''Sopranos" season has much the same effect.
Now comes ''The Best of Youth," from Italy, and it is a slowly flowering miracle: an epic of normal life. Like the films mentioned above, it started as a TV project, an Italian miniseries written by Sandro Petraglia and Stefano Rulli and directed by Marco Tullio Giordano. Unlike the others, it never aired, for reasons of ''political subversion." This seems silly but understandable; ''The Best of Youth" is explicitly about how people are more important than their political beliefs. Traversing 35 years of the country's recent history, the film contains much that will mean nothing to non-Italian audiences. Because the characters come first, though, it is universal. It's also an emotional killer.
One caveat: The film does take its sweet time getting up to speed. ''Best of Youth" will be shown at the Coolidge in two three-hour chunks, and after the first installment you may wonder what the fuss is about.
We've followed the Carati brothers from 1966 to 1980, from Rome to Florence to Turin and beyond, watching as they dance between idealism and compromise. Nicola (Luigi Lo Cascio), a medical student, is the cautious, thoughtful younger one, while older Matteo (Alessio Boni) seethes handsomely with dissatisfaction -- he wants to change the world, but he doesn't know whether to apply intellect or force. (That may be the history of modern Italy right there.)
In the first three hours, Nicola and Matteo travel together, only to diverge. The older brother ''rescues" a severely disturbed young woman named Giorgia (Jasmine Trinca) from the institution at which he works, bringing her along on a post-college road trip. This is a bad idea that, over the long haul, turns out to be surprisingly sensible, and Giorgia becomes something like the film's easily bruised conscience.
There are other women as well. Helping out in Florence after the devastating 1966 flood, Nicola meets Giulia (Sonia Bergamasco), a blond sylph who plays classical piano but doesn't trust the music's beauty. Their romance weaves in and out of counterculture idealism and its violent aftermath; the Red Brigade hovers in the background like an adulterous lover.
Matteo, for his part, meets a photographer named Mirella (Maya Sansa) -- dark, earthy, Sicilian -- and must decide whether to join the world or continue trying to fix it. The most mysterious of the film's characters, he is also its most troubling. Matteo's green eyes flash with the panic of a man realizing he may have chosen the wrong side.
In the second three hours of ''The Best of Youth," covering 1982 to 2003, the narrative waywardness begins to cohere. Lives turn into patterns, then back into lives; parents age and die, siblings and children blossom, friends succeed or falter. The locations expand to include trendy Tuscany and the island of Stromboli with its allegorical volcano. Even at the price of two tickets, the film's a cheap vacation.
Giordano plays with the pacing in interesting ways; New Year's Eve 1983 goes on forever, and you're not sure why, until, suddenly, you are. There are other gasp-inducing developments, but what most grips a viewer's heart is the sadness and bounty of life passing. Events like the 1992 Palermo protests against the Mafia unfold in the background, occasionally intersecting with the characters' destinies. ''The Best of Youth" is not an epic of its times, but a tale of ordinary people living through those times.
Fittingly, the hero is a decent man, and his decency becomes the film's unexpected subject. In Lo Cascio's quiet, hugely appealing performance (the actor suggests a less neurotic Jean-Pierre Léaud), Nicola is a single father and clinical psychiatrist who has always tried to do the right thing. At a certain point he is forced to wonder, as we all must, whether the right thing is enough.
But the final scenes of ''The Best of Youth" suggest that if misfortune is an accidental byproduct of human existence, so too is goodness. There's sentimentality in that notion, but it's grounded by an achingly cosmic long view that, for characters and viewers alike, has been earned the hard way.
Ty Burr can be reached at email@example.com.