Manatee County's new public nudity ordinance went into effect Saturday. From now on, no one there may see more than three-fourths of a breast and one-third of a pair of buttocks in public.

It's as if we never left the 20th century.

In 1990, Sarasota had a similar concern and banned T-back swimsuits, which got us on the "Donahue" TV show. The then-mayor of Sarasota, Kerry Kirschner, argued against the ban, citing the city symbol, Michelangelo's "David." He told host Phil Donahue, in so many words, that if a city wraps itself in a flag of nudity, it shouldn't dictate dress codes.

And then Donohue said a remarkable thing: "Yeah, but 'David' doesn't move around." Out of the mouths of talk-show hosts.

Nudity in motion is the crux of the concern over clefts. Peeled-down people are ripe for picking on, while people sculpted stripped pose no threat. That's the word from English museum curator Gil Saunders in his book "The Nude: A New Perspective." Exposed flesh on canvas or in clay expresses "passivity and vulnerability," his book says. Saunders illustrates his point with Rubens' painting "Cain Slaying Abel." Abel, the victim, is unclad. Cain is not.

It's easy to think of other examples: the Ringling Museum of Art's naked woman in "Perseus and Andromeda," by Cavaliere d'Arpino, chained to a rock and being attacked by wild animals, is an effigy of passivity; and the naked woman under siege in "Susannah and the Elders," by Sisto Badalocchio, is an icon of vulnerability.

Nude-watching made safe.

Maybe that's why the city of Sarasota used a rear-end image of "David," cleft and all, on its letterheads for so long, yet outlawed T-backs. Looking at in-the-flesh flesh is a nude of a different color: blushing red.

Saunders says this happens because we live with two clashing ideals: the Renaissance ideal that bodies stand for truth and beauty, and the medieval view that bodies stand for shame and guilt.

We seek the classical mode by dieting and exercising, but we remain modest about our anatomy.

Art from these two historial periods tell the story. Renaissance artist Michelangelo showed that the nude form represents perfection by matching it to a pattern of circles and squares. Sarasota's worship of "David" fulfills this ideal.

Medieval artists showed nakedness only in pictures of The Last Judgment and the torments of hell -- the moral being that nakedness should be punished. Sarasota's ban on T-backs reflects this view.

Female nakedness gave the Middle Ages its biggest problem. The painting "The Martyrdom of Saint Agatha," shows the mutilation of a woman's breasts because of the temptation they present to men.

The medieval concern about women as temptresses carried over into the Renaissance. Female nudes were made from male models. You can see it in Michelangelo's sculpture "Night and Day," in which the woman is excessively muscled.

Given our collective history, it's not surprising that when it comes to beholding bare-breasted or backsided bodies on the beach or in bars, we think that's bad. But when it comes to beholding bodies in the buff in art, we think that's OK. Only a thin line separates them. One nude is operative, the other is not.