In the early years of his career, Pei claims, he was "an empty vessel" with no defined aesthetic of his own, aside from a debt to the Bauhaus movement, which he encountered when studying with Gropius in graduate school. He had always been interested in light, however. "The essence of architecture is form and space," he says, "and light is the essential element to the key to architectural design, probably more important than anything. Technology and materials are secondary."

For Pei, technology has its uses, but it never drives design. He readily admits that he is "anticomputer" and does not use ­computer-­aided design tools for conceptual work. "MIT will be surprised to hear that, and probably not very happy," he says. "What does a computer show you that you yourself can think about? For making drawings today, I can't imagine practicing without a computer. In a technical sense, it is a very wonderful tool. But in the conceptual sense ... does the computer help poetry?"

Pei, who comes from a long line of artists, poets, calligraphers, and musicians on his mother's side, says that he is an admirer of poetry, particularly Whitman, Thoreau, Li Bai, and Du Fu. He recites Chinese poetry and writes his own poems in Chinese. Like poetry, architecture depends on inspiration from an internal source, he says.

For the Museum of Islamic Art, Pei drew on his knowledge of Islamic buildings in Spain, India, and places in between. But traveling to North Africa to learn more, he saw that Islamic architecture follows the sun. For an architect whose best works are defined by the play of light, the commission was ideal.

"The architecture is determined by the sun," he says. "I had to look for the essence of Islamic architecture .... All the way from Cordoba to Fatepuhr Sikri is all sun, but the sun does different things in different places." In the desert, the sun reveals form, and form, he says, takes on a special importance there: "Geometry and mathematics actually origi­nated in this part of the world. So I decided to find the magical example, if there is such a thing. I found it in Egypt.

"There is a mosque called Ibn Tulun. Inside the mosque is a big courtyard, and there is a little ablution fountain. It starts as a square inside another square, then an octagon, then a circle. It's a small thing. The total height of that little ablution fountain could not be more than 60 or 70 feet, but because of that piling up of geometric forms, under the sun, it is magical. You walk around it, and it changes all the time. Therefore, my building learned from that building," says Pei.

"That little building is a poem."

To create his own poem, Pei collaborated with the sun. "The form comes to life under light," he says of his Museum of Islamic Art, which opens in Doha, Qatar, this fall. "It doesn't matter where you build, but when you are building under the desert sun, it becomes more important. Form doesn't need to be complicated. The light gives it so much life. In northern architecture--the cathedrals of Europe and all the little churches--the details, the carving of stone, become necessary because the light is not there to help you very much. You have to enrich surfaces. The desert reduces form to its simplest nature. There is no need for gargoyles or flying buttresses in the desert.