Upon hearing him say that, one is tempted to go for a pistol, but after a day of McDonough's instruction in much more than architecture, one sees that his utopianism is grounded in a unified philosophy that--in demonstrable and practical ways--is changing the design of the world. McDonough empathizes with birds because he's a rare one himself, a visionary--half green, half pink--who talks like a communist, thinks like a plutocrat and acts like an ecologist. Indeed, the three points of his abstractly designed universe (he is given to drawing incomprehensible diagrams on any available surface) reflect that people who used to be impelled to make things by the old impulses of social and economic interests now must add the environment. "But not as an ism," he cautions, not as an extreme. "What we're trying to do is balance ecology, equity and economy."

The Gap campus, which William McDonough+Partners completed in 1997, is an anomaly of a building that looks more beautiful in life than it does in photos, and seems to expand its beauty from the inside out. The inside is essentially the outside, so when one is there, one is also somewhere else. The "facts" of the structure read like an essay on "What I Did for the Environment Last Summer": the roofs are planted with native grasses and wildflowers atop 6 in. of soil that both fools the birds and serves as a thermal and acoustical insulator. San Bruno is a stone's throw from San Francisco's airport, yet planes flying low overhead create barely a buzz.

The complex's wood floors and veneer were harvested from sustainable forests. Not a single California live oak was cut down during construction, and a stand of the ancient trees rises in a dark elegance just beyond a piazza. Huge atriums carry daylight deep into the building, paints and adhesives are low toxicity, the place is 30% more energy efficient than state law requires, and so on.

But the special power of the structure is its palpable connection to the people who work there. On the day that McDonough and I visit, 600 employees go about their tasks, yet the building feels empty. The windows bring people to the sky. "When it's a nice day," says McDonough, "why feel as if you've missed it?" Stand in practically any spot, and one can see the greenery of the outside trees, the grassy lower roof or the grasses growing in one of the two interior courtyards. Light is everywhere. It fills the vast open hallways that seem to stretch on forever under ceilings 15 ft. high. McDonough says, "People have lofty thoughts in lofty places."

A walking college lecture--he is also dean of the University of Virginia school of architecture--McDonough is a compendium of similar maxims, phrases and rules: "Honor commerce as the engine of change"; "respect diversity"; "build for abundance"; "eco-efficiency should be replaced by eco-effectiveness"; "design is the first signal of human intention"; "all sustainability, like politics, is local"; "I want to do architecture that is timeless and mindful."

All this and much more come from a 48-year-old innocent anarchist; his language has the touch of the poet and of the bomb thrower; he looks like actor James Woods in a bow tie. He thinks abstractly, making it equally fascinating and difficult to talk to him, since he turns nearly every contribution one makes to the conversation into a refinement of his theories.