Many items in MFA’s ‘Floating World’ show have not been on display since late 19th century.

Deep in the bowels of Boston’s Museum of Fine Arts, a treasure has been hiding for more than a century. The treasure glows with gold, sparkles with mica, dazzles with color and seduces with images of rare beauty. It is now on the walls of the MFA’s Torf Gallery, luscious paintings that date back to the late 17th century, silken renderings of geishas, courtesans and actors, in gardens, on stage and in brothels, wearing lavish costumes and engaged in performance, flirtations and lovemaking.

These are gorgeous creatures whose hairdos, clothing and poses reveal their station in society; a bright, elaborate kimono, for instance, indicates that the wearer is a courtesan, a lady bred for sexual pleasure, while a geisha’s more somber garment reveals her sole obligation is to be entertaining.

‘‘Drama and Desire: Japanese Paintings from the Floating World 1690-1850’’ comprises 83 items from the MFA’s sublime ukiyo-e collection, most of which has not been exhibited publicly since the late 19th century, when these works and thousands of others were donated to the museum by William Sturgis Bigelow, a Boston physician who lived for several years in Japan.

As stunning as this exhibit is, equally as impressive is the survival of the works over time and the effort required to restore them to their original glory.

This show has been a labor of love for Anne Nishimura Morse, the William and Helen Pounds curator of Japanese art in the Department of Art of Asia, Oceania and Africa. That long title suggests in a small way her responsibilities at the museum, which requires her to oversee 100,000 items in the Japanese collection.

Morse, who came to the museum in the mid-1980s, was aware that the MFA had a prodigious collection of Japanese art, one of the largest and most admired in the world. What is particularly significant is its holdings of paintings by all the major ukiyo-e artists, the only collection in the world to be so endowed.

Ukiyo-e means painter of the floating world, one who with paint or ink recorded the pleasurable underside of life in Edo (today’s Tokyo), an area established in the early 17th century as a military capital. It grew over the next century to become a major political and commercial center. To escape the hardships of their workaday world, men would seek respite in a gated brothel area, where they could indulge not only in the obvious, but attend the Kabuki theater, poetry sessions and musical performances.

The artists who first recorded these leisurely pursuits through paintings invented a highly stylized genre, wherein a gesture, a drape of robe, a fabric detail served as an encryption of sorts for contemporary viewers who would be able to understand their significance regarding the figure being depicted.

On display are screens, scrolls, banners and theater sign boards by all the major ukiyo-e painters, including Hokusai, Utamario and Hiroshige. Together they take the viewer to a place of sublime fantasy, where everyone is beautiful and carefree and happy.

On this day, guiding reporters on a tour of the show, no one is happier than Morse.

Diminutive, chic and smiling, the curator talks about the journey that took these works out of the shadows and into public light.

‘‘The survey itself,’’ she begins, ‘‘of about 4,000 works (in the ukiyo-e painting, decorative arts and sculpture collections) has taken 14 years with the help of 28 scholars, all but one from Japan. Every summer - because that was the time they could get away - they would spend about two months here.’’

Clearly touched, Morse continues, ‘‘There would be these gasps (when the scholars examined certain works), because they couldn’t get over how well-preserved they were, how vibrant the colors were.’’

On another occasion, she came upon visitors who appeared very excited about a discovery they had made. Her assistant explained to Morse that they recognized a work by Haronobu, one of the earliest of the ukiyo-e painters.

‘‘I said, of course it’s a Haronobu. ‘You don’t understand,’ my assistant said. ‘They never have seen one before.’’’

Among the more unusual objects is a scroll of graphic erotica, a man and woman engaged in athletic lovemaking.

‘‘There are 100 of these pieces out of 700 (in the ukiyo-e painting collection),’’ says Morse, going on to describe her introduction to these works.

‘‘I am the first woman to be allowed to view them,’’ she laughs, ‘‘and that’s because I’m married.’’ In the past, it seems only male curators were given a key to where they were stored.

Among the most exquisite objects in the show are renderings on silk or paper using mineral pigments with a glue binder for the paints, and carbon from soot for inks. These works are enhanced by being mounted on rich, colorful fabrics that complement the tones in the paintings. It is these mountings that are most fragile, and, depending on their condition, have been restored or replaced by the museum’s staff of conservators, who have been working on the project for the past five years, Morse says.

She stresses that, indeed, it is the fragility of the works that makes this show so important.

‘‘Because they can be exposed so rarely, I can’t imagine that we’ll be able to show them again for about 30 years. So, you might say this is a once-in-a-generation event.’’

Moving close to one of the works, which is hung inside a huge, clear box, Morse urges the reporters to get as close as possible.

‘‘It is the details that are so fascinating,’’ she says, indicating the fine wisps of hair combed up into a chignon, a tiny cherry blossom glimpsed inside a flowing kimono sleeve, the curled toes of a girl reading a love letter.

‘‘That is where you can see the hand of the artist.’’

If you go ...

What: ‘‘Drama and Desire: Japanese paintings from the Floating World 1690-1850’’ Where: Boston’s Museum of Fine Art When: Continues through Dec. 16 before heading to Asian Art Museum of San Francisco from Feb. 15 to May 4. Details: For more information, visit the museum’s Web site at www.mfa.org, or call 617-267-9300