"People underestimate the power of clothes to tell stories,” says Andrew Bolton, the slender, skinny-suited curator of “China: Through the Looking Glass.” The exhibit, which opened at the Metropolitan Museum of Art last spring, examined how China’s aesthetics have influenced Western fashion — and kicked off with a celebrity-studded fundraising party from whose date Andrew Rossi’s documentary takes its title: “The First Monday in May.”

It’s a film that effectively combines two distinct — and very different — pleasures. For those fascinated by the art of clothing, “May” offers staffers from the Met’s Costume Institute (the largest collection of fashion in the world, we’re told) discussing why costume was long relegated to the category of “decorative art,” and debating the issues of cultural appropriation that made “Through the Looking Glass” inevitably controversial. We watch as gloved technicians meticulously unpack the borrowed garments for the exhibit, handling them gently and reverently, as if they might break.

There’s equal delight, of a less highbrow nature, in watching Vogue magazine editor Anna Wintour and her staffers as they plan the fundraiser — debating which celebrity merits an invitation (the mention of Josh Hartnett elicits a “what has he done lately?”), choosing just the right napkins and pondering the subtleties of the rainbow-hued seating plan. (Wintour, for the record, seats George Clooney next to herself. As one should.)

You wish the film gave more than quick glances to the many stunning gowns on the red carpet once that first Monday finally arrived; it’s like racing through a museum, with only fleeting peeks at the art. Instead, the movie takes a lovely pause near its end. Earlier, we saw Bolton meticulously adjusting an exquisite waterfall of a gown — making a tiny change to its folds, walking away, gazing, coming back, adjusting again. Now, we watch him walking alone through the quiet, completed exhibition, breathing in the beauty. It needed to be perfect, and it is.

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‘THE FIRST MONDAY IN MAY’

3 out of 4 stars

A documentary directed by Andrew Rossi.

91 minutes.

Rated PG-13 for brief strong language.

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