The Same River Twice takes its name from a quote attributed to the pre-Socratic philosopher Heraclitus, who saw the universe existing in a constant state of flux, even when it appears to stay the same. "You cannot step into the same river twice," the saying goes, and the Robb Moss-directed documentary would make Heraclitus' point even without the allusion. In the 1970s, Moss and his group of outdoors-loving, unreformed hippie friends spent their summers rafting through the Grand Canyon. Clothing was optional (and usually disdained), and the group lived off what little it could carry. Moss nevertheless found room for some camera equipment, and filmed their watery idyll for posterity. With The Same River Twice, Moss revisits five of his friends, contrasting their lives today with the way they lived then, and the results look less like a big chill than a slow drift. Most have migrated to the suburbs but stayed politically active; two even became mayors of small cities. Lovers have split, one has faced his mortality through a successful battle with cancer, and by the film's end, even the friend most committed to the river-rat lifestyle has started to put down roots by building a house. Moss offers few startling revelations, but gently gets at the truth of his subjects' lives by playing the past against the present. Most seem comfortable with both phases, if unsure how either relates to the future. (One comments that when her children ask her about drugs, she'll have the choice either to lie and say they're horrible, or tell the truth and take a chance that they'll show less restraint than she did.) There's a wistfulness to the way the film's participants talk about the past in the face of images of their unrecoverable, lithe, youthful bodies, but Moss' film also reveals people whose personalities remained fundamentally intact across decades, and who seem comfortable participating in the passage of one generation into the next. Heraclitus may have been on to something, but so was whoever first observed that the more things change, the more they stay the same.