It is easier to admire than to love Robert Mapplethorpe's famous late work. The photographs are gorgeous, some of them stunningly poignant, but they are so controlled, so tight—so much direction funneled fiercely into a selected moment—that even when you get right up next to them, or maybe especially when you get right up next to them, they still feel far away. If you want a Robert Mapplethorpe to love, you need the early Polaroids. The Polaroids are the warmest and the hottest things he ever made, these fuzzy palm-sized original prints of him and his friends and lovers in the zone between playing and posing. Each one, whether it's a naked self-portrait—he's hooded and chained, staring straight at the lens—or the spray of flowers laid on a pillow, is a close and confident exchange of some kind. Each one is a back-and-forth between photographer and subject (and image and viewer) that's charged with the frisson of the personal.

It's perfect, then, that the Polaroids have been hung in the gallery in pairs: coupled. After all, with the same subjects he would later turn into high art objects—nudes, flowers, friends (Patti Smith, Marianne Faithfull, a million beautiful men—especially his longtime love, the square-jawed beauty Sam Wagstaff, a curator), himself, sex—Mapplethorpe here creates mementos that exist in the spaces between people. (That's not to say he didn't see them as finished works: Some are plainly exhibition-ready and did appear in New York galleries in the early '70s.)

About 90 of the Polaroids are showing now at the Henry Art Gallery. Each pair is arranged vertically, one above another, with breathing room between pairs. In the first room is a shot of Mapplethorpe, reclining shirtless on the bed, with the phone to his ear. Above it is a head-on shot of Wagstaff from the chest up, his shirt open, standing outdoors. Wagstaff's gaze is direct, but the light seems to fall behind him, leaving his face partially veiled. Hung together, the two pictures draw each other out. They create a sliver of story.

"It's not fact, or anything that Robert wrote—it's just the way I feel about the picture," says Sylvia Wolf. "With these two, I was thinking about the times when they were apart, when they would talk on the phone. And then I was thinking about, in couples, what you keep to yourself—this shrouding—and what you share."

Wolf is the curator of Polaroids: Mapplethorpe. She started working on the show in 2003, when, as curator of photography at the Whitney Museum of American Art, she went into a back room at the Mapplethorpe Foundation one day and discovered a trove of a thousand forgotten Polaroids in boxes and binders. She recognized their importance and allure immediately; the show opened at the Whitney in 2008, the same year she became director at the Henry, the final stop on the show's tour.

Mapplethorpe makes overt use of pairs, like Felix Gonzalez-Torres after him: two wicker chairs nestled next to each other, two hanging bats, two pillows, the occasional double exposure. In this way, Wolf's layout follows the artist's cue. Some of her pairings at the Henry (slightly different from the pairings that appeared at the Whitney) are playful. A tongue stuck out hangs with a fist squeezed to make a hole. Others are formal: Here is the deep perspective out a window; here is the flat perspective of a painted wall. An image of a monument seen from below hangs above an image of a street seen from above, as if to position you between them. Tonal and emotional shifts are hinted at: Two men sitting tenderly on a white bed are paired with a stark Christlike figure on a black background with pins on his nipples.

Many of the interpretations carry associations both plain and arcane. A shot of a woman's bare, curving body hangs above an image of a nude subject positioned as if he is melting off a pedestal—the two made Wolf think about the art-historical tradition of the flaming body, the liquid spirituality of the martyred St. Sebastian. Sex and seduction are never far from view. Wolf paired the artist's portrait of his own feet with a shot of boots and jeans in a heap—a "souvenir of foreplay after the fact," as she puts it.

The pairings—as opposed to what can be the "tic-tac-toe" quality of a grid arrangement of photographs—encourage deep looking, but still proceed in sequenced rows. Chronology is loosely followed; after all, these photographs were made over only six years, from 1970 to 1975. After Wagstaff gave Mapplethorpe a Hasselblad camera in 1975, the artist never returned to Polaroids. He died in 1989.

Some of these Polaroids are the best images Mapplethorpe ever made: a hand on a striped mattress pulling a white sheet taut—an act of pure sexual ache; one-two shots of leather underwear, one zipped, the next unzipped and full of curving flesh. Seattle is the end of the line for this show, but the book lives on, with even more images, including a sequence of Mapplethorpe dressing and undressing for the camera, and two incendiary photographs of Mapplethorpe, naked, squatting and standing over a crucifix. Polaroids is Mapplethorpe's other half. recommended