Terrence Malick's long-awaited Tree of Life was finally unspooled at the Cannes Film Festival today (Monday), receiving polite applause mixed with scattered boos from an overflow crowd of reporters attending a morning screening. Most, however, were No Doubt left mystified by Malick's laudable attempt to portray the mundane life of a nuclear family of the 1950s against the nucleus of the living world itself. A lengthy section of the film amounts to a visual poem about the paradox of creation and destruction, the sort of cosmic montage that used to screen behind The Grateful Dead at a Ken Kesey Acid Test at the Longshoreman's Hall in San Francisco in the '60s. What's it all about? Malick himself did not come to Cannes to explain. Producer Grant Hill, who did, justified Malick's absence at a news conference by remarking, "He puts the film out there and expects people to make what they want to make of it." Brad Pitt, the star of the film -- he plays what he described as "an oppressive father" -- told reporters that movies may be the only art form where the artist is expected to act as his own salesman, a role Malick shies away from. Also a no-show Sean Penn, who plays the grown-up version of one of the three boys in Pitt's family. His role is barely more than a cameo -- and he was not even mentioned at today's news conference.