When the architect and theorist Le Corbusier imagined the future of cities from the vantage of the early 20th century, he foresaw a new industrial aesthetic that would free design from the constraints of the natural world. For Le Corbusier, the city was "a human operation directed against nature" and the house was "a machine for living in." He imagined architecture worldwide shaped by a "mass production spirit." The ideal: "One single building for all nations and climates." Le Corbusier's friends dismissed his futuristic ideas. "All this is for the year 2000," they said.

It seems they were right. In many ways, our world is LeCorbusier's world: From Rangoon to Reykjavik one-size-fits-all buildings employ the "engineer's aesthetic" to overcome the rules of the natural world. As uplifting as that might be for the spirit of LeCorbusier, it is becoming more apparent all the time that buildings conceived as mass-produced machines impoverish cultural diversity and leave their inhabitants cut-off from the wonders and delights of nature.

But what if buildings were alive? What if our homes and workplaces were like trees, living organisms participating productively in their surroundings? Imagine a building, enmeshed in the landscape, that harvests the energy of the sun, sequesters carbon and makes oxygen. Imagine on-site wetlands and botanical gardens recovering nutrients from circulating water. Fresh air, flowering plants, and daylight everywhere. Beauty and comfort for every inhabitant. A roof covered in soil and sedum to absorb the falling rain. Birds nesting and feeding in the building's verdant footprint. In short, a life-support system in harmony with energy flows, human souls, and other living things. Hardly a machine at all.

This is not science fiction. Buildings like trees, though few in number, already exist. So when we survey the future-the prospects for buildings and cities, settled and unsettled lands-we see a new sensibility emerging, one in which inhabiting a place becomes a mindful, delightful participation in landscape. This perspective is both rigorous and poetic. It is built on design principles inspired by nature's laws. It is enacted by immersing oneself in the life of a place to discover the most fitting and beautiful materials and forms. It is a design aesthetic that draws equally on the poetics of science and the poetics of space. We hope it is the design strategy of the future.

The Human Leaf
If one unpacks the compressed verse of Einstein-E=MC2-one finds poetry, beauty, the dynamic structure of the universe. Following Einstein's inimitable lead, we see in E=MC2 a kind of design koan. E is the energy of the sun-physics and planetary motion. M is the mass of the earth-chemistry. When the two interact at the speed of light, biology flourishes and we celebrate its increase-the growth of trees, plants, food, biodiversity and all the cycles of nature that run on the sun. Good growth. And when human systems support ecological health, that's good growth too.

Applied to design, the laws of nature give architects, designers and planners a set of principles that allow them to articulate in form a building's or a town's connection to a particular place. They allow us to create buildings that make the energy of the sun a part of our metabolism and apply it to positive human purpose-the building as "human leaf." The principles, illustrated by the life of a tree, are:

Waste=Food. The processes of each organism in a living system contribute to the health of the whole. A fruit tree's blossoms fall to the ground and decompose into food for other living things. Bacteria and fungi feed on the organic waste of both the tree and the animals that eat its fruit, depositing nutrients in the soil in a form ready for the tree to take up and convert into growth. One organism's waste becomes food for another. Applied to architecture, these cradle-to-cradle nutrient cycles can serve as models for the design of materials and building systems that eliminate the concept of waste. Materials designed for use in cradle-to-cradle cycles, for example, can be either safely returned to the soil or re-utilized as high-quality materials for new products.

Use current solar income. Living things thrive on the energy of the sun. Simply put, a tree manufactures food from sunlight, an elegant, effective system that uses the earth's only perpetual source of energy income. Buildings that tap into solar income-using direct solar energy collection; passive solar processes such as daylighting; and wind power, which is created by thermal flows fueled by sunlight-make productive and profitable use of local energy flows.

Celebrate diversity. "The tree" provides not just one design model but many. Around the world, photosynthesis and nutrient cycling, adapted to locale, yield an astonishing diversity of forms. Bald cypress, desert palm, and Douglas fir suggest a range of niches. The hundreds of tree species within a single acre of Southern Appalachian forest suggest the diversity of a single region. Architects and planners, applying a diversity of design solutions, can create buildings and cities that fit elegantly and effectively into their own niches.

Kinship with All Life
As architects and planners explore these principles-what amounts to a new conception of design-they will become more adept at creating fit and fitting spaces for human habitation. New benchmarks will emerge. Rather than overpowering nature or limiting human impact, good design will affirm the possibility of developing healthy and creatively interactive relationships between human settlements and the natural world

With new benchmarks will come new practices, and a design process that is now rare will, we hope, become the norm. Design teams in many regions would begin with an assessment of the natural systems of a place-its landforms, hydrology, vegetation, and climate. They would tap into natural and cultural history; investigate local energy sources; explore the cycles of sunlight, shade and water; study the vernacular architecture of the region and the lives of local fauna, flowers and grasses.

Combining an understanding of building and energy systems with this emerging "essay of clues," designers would discover appropriate patterns for the development of the landscape. Building materials would be selected with the same care, chosen only after a careful assessment of a variety of characteristics, ranging from their chemistry to the impacts of their use, harvesting and manufacture. We might also expect to see the industry-wide pooling of architectural products as builders begin to create closed-loop recycling systems to effectively manage the flow of materials.

With this emphasis on sustaining and enhancing the qualities of the landscape, architectural and community designs would begin to create beneficial ecological footprints-more habitat, wetlands and clean water, not fewer negative emissions. We would see buildings like trees, alive to their surroundings and inhabitants, and cities like forests, in which nature and design create a living, breathing habitat. Vital threads of landscape would provide connectivity between communities, linking urban forests to downtown neighborhoods to riparian corridors to distant wilds. Cities and towns would be shaped and cultivated by an understanding of their singular evolutionary matrix, a new sense of natural and cultural identity that would grow health, diversity and delight, and set the stage for long-term prosperity.

Changes such as these, many already afoot, signal a hopeful new era. Ultimately, they will lead to ever more places that honor not just human ingenuity but harmony with the exquisite intelligence of nature. And when that becomes the hallmark of good design, we will have left behind the century of the machine and begun to celebrate our kinship with all of life.