Dreyfus says that he feels a certain responsibility to a family name that still reverberates with France's political scandal of the 1890s, when Captain Alfred Dreyfus, a Jewish staff officer in France's military hierarchy, was accused of spying for Germany.

"Jews say that God is light, and people say that light is God's shadow," Dreyfus says. "But light doesn't have words. It does not speak intellectually. It is about emotion."

In the fashion world, designers look to Dreyfus to express a mood or a feeling as well as to put clothes and models, literally, in the best possible light. He works instinctively, often being asked to interpret with his skills the designers' vision.

Ann Demeulemeester, the Belgian designer who has worked with Dreyfus since 1989, says, "I can talk to him with other words than as a technician."

"With lights you really can make a certain atmosphere," Demeulemeester says. "I don't like what I call fashion light that is really oppressive, but something more poetic. I'm not an easy person to work with. But Thierry is not just a person who is putting up some lamps."

Dreyfus has worked with Calvin Klein to warm the models' skin and make the clothes seem touchable; he helped concretize the instinctive ideas of Miguel Adrover; he brought a 1950s glamour to Giambattista Valli's summer 2005 show; and he follows precisely Slimane's concepts for Dior Homme.

"He has the capacity, he is passionate and obsessional - and he understands," says Slimane, for whom Dreyfus produces graphic visual scenarios. The lighting designer expresses their working relationship like this: "When Hedi asks for red, I know what red he is talking about."

Dreyfus discusses light as a practical tool, asking how a woman can put on her makeup in the artificial light of a bathroom. He also speaks as an artist does, describing Paris as a "yellow" city, Tokyo with "neon everywhere" and Africa tinged green with neon "that has not been changed for years."

"My definition of artists is of people who need to create as others need to go to films or see friends," insists Dreyfus.

Yet he himself suddenly felt the need to record the Grand Palais project by photographing it in all its lyrical, luminous color. Those images will be published in a book from Assouline in the new year, and Dreyfus is thinking tentatively of a finding a gallery. His art seems to be coming out of the shadows into the light.

Suzy Menkes - International Herald Tribune - Monday, December 12, 2005