Montaigne said it best: “It’s a spiny business — more so than it seems — to follow a movement as vagabond as that of our spirit, to penetrate the opaque profundity of its innermost folds, to pick out and immobilize the innumerable flutterings that agitate it.”

“This Film Is Not Yet Rated” takes on that prickly business and finds that, at least when it comes to movies, what agitates us most is Chloe Sevigny’s face, diagonal across a screen, lost in the ecstasy of cunnilingus. Or rather, that’s what agitates the members of the Motion Picture Association of America’s ratings — a cabal as shadowy as the Black Mass in “Eyes Wide Shut,” except totally grossed out by rhythmic thrusting, puppets doing reverse cowgirl, pubic hair and clothed female masturbation. To expose the anonymous people of the MPAA is Becky Altringer, the plucky, lovable, hockey-haired Hollywood snoop behind Ariel Investigations. And while we’re waiting for their unmasking, there’s oodles of erudite filmmaker rhetoric from John Waters, Kevin Smith, Kimberly Peirce and Trey Parker and Matt Stone.

Aren’t the ratings voluntary? Well, they explain, only inasmuch as skydiving without a parachute. It can be done, but it won’t end well. Theaters and DVD-retailers won’t touch an unrated movie — think that’s related to their executives’ prominence on the MPAA’s boards? Look, if you need to outsource the basics of parenting, there are

plenty of experts online to cater to your any censorship kink. LDS? Vegan? Deaf? Native American? There’s a guide for that. But the current system, because it is explicitly and proudly geared toward parents, “is turning us all into children,” critic David Ansen says in the movie.

Roger Ebert put the problem of the ratings board best when he railed against their NC-17 rating for “Eyes Wide Shut,” which was avoided by blocking out parts of the film’s orgy scenes with digital people in robes, saying it’s “symbolic of the moral hypocrisy of the rating system that it would force a great director to compromise his vision, while by the same process making his adult film more accessible to young viewers.” Ebert was an early and vocal promoter of an adults-only rating for non-porn movies and the only lacking of “This Film Is Not Yet Rated” is that, while it so clearly painted the problem, it stopped short of a solution. Here it is: an adults-only

rating.

But to take that solution, you’d have to be genuinely interested in your stated purpose of steering parents away from accidentally exposing Junior to nightmare fuel, a murky science at best. I was terrified by the torture machine in “The Princess Bride.” It took me 20 years before I gave it a well deserved second shot, but parents

should come up with some basic rules — no war documentaries, unless you’re fine with Kiddo spouting off about “killing Haji,” and no erotic thrillers — and enforce them themselves. I’d rather watch Divine eat dog doo in “Pink Flamingoes” over Neve Campbell and Denise Richards doing the nasty in a swimming pool, but I can deal with

someone having the opposite opinion. So long as they’re not the priests (yup, there are two, with votes, on the MPAA’s appeals board) deciding which movie sees the darkness of a movie theater.

Near the end of “This Film Is Not Yet Rated,” head honcho Jack Valenti tells us what he wants on his tombstone. “He freed the screen from all artificial barriers.” I’m not sure what that’s supposed to mean, but if it’s true, it’s only in the sense that his and the MPAA’s barriers are maddeningly, condescendingly, lunk-headedly, closed-mindedly real.

Ashley O’Dell reviews movies that aren’t in theaters anymore.