Planning to Learn

An Ecological Approach to Analyzing Land Use Alternatives


To plan successfully we learn to predict accurately. Only to the extent that we can correctly anticipate the outcomes of contemplated action can we make real and meaningful choice.

Many agree that the scientific method is unparalleled as a means to discern and describe the repeated patterns by which we are able to foresee consequences. During the past century people have accelerated the integration of scientific disciplines and the extension of the scientific domain to encompass more and more of the human experience. Ecology, the scientific study of interaction between life and the environment, is a product of these trends.

Increasingly, planners are finding ecological analysis, with its broad applicability to human concerns, and its reliable results, a uniquely sound framework for decision at every level from individual life to global enterprise. Of the foundations of ecology, the laws of classical thermodynamics, Albert Einstein had this to say:

"A theory is more impressive the greater is the simplicity of its premises, the more different are the kinds of things it relates and the more extended its range of applicability. Therefore the deep impression which classical thermo- dynamics made on me. It is the only physical theory of universal content which I am convinced, that within the frame- work of applicability of its basic concepts, will never be overthrown."

The political and economic analyses on which many of us have relied heavily in recent decades will likely persist as grounds on which we negotiate with each other for relative advantage. But we carry out our plans on a field larger than human society: we also interact with other life and with the Earth. While we may triumph over one another in the legislature, the courts, the administrative agency, or the marketplace, and while we may even appear temporarily to have conquered Nature, we will discover these to be illusory and hollow victories unless we play in accordance with ecological principle. Natural law is always enforced. As the human population grows and our impact on natural systems increases, we encounter with increasing frequency the limits imposed by Nature.

The primary purpose of this writing is to invite a step back from habitual thought and perception, that we may consider community planning afresh. People can structure a more democratic and more fruitful planning process by affording participants shared access to accurate information about the advantages and sacrifices inherent to available choices. We offer here an approach to acquiring such information, and invite our readers to test its validity against your own experience. We intend this document as a prelude to a plan, a solid foundation from which planners can proceed to ascertain and articulate goals and objectives which express the preferences of a given community within the realm of the possible.

We begin by outlining a rudimentary framework for ecological analysis. Next we apply this framework to explore what fundamental values humans share, and to assess how well we are furthering those values by our current ways of being. Then we turn to the question of settlement patterns, and examine both how we have arrived at our current situation, and how we may plan towards a more satisfying future. We close with an invitation to partnership.


In an ecological approach we select some organism or population as a focal point. Everything with which this individual or group interacts we then define as the environment.

For our purposes the human species is central. The natural and artificial entities with which humans interact comprise the environment. We may conduct a simple, yet illuminating ecological analysis of the human condition in terms of four factors. Two, population size and information, pertain to humans. Two others, resource and hazard, are qualities of the environment.


Our numbers are critical. We live on a finite planet. By increasing human population size we decrease per capita natural resource.


Here we define information to mean the instructions we carry for interacting with our surroundings.

Much of our information is genetically determined and remains permanently fixed. In utero experiences, like those resulting from our mother's diet or the presence of drugs in her blood, also may shape us for life. An example of how genetic information determines our responses to the environment is susceptibility to sunburn, which varies with skin pigmentation.

We also may accumulate a more flexible kind of information by observing ourselves and our surroundings, and remembering. We may add to and subtract from this information with each experience. For example, we may learn to speak one language as children, and another as young adults.


Each of us perceives certain environmental elements to be useful. Virtually everyone can appreciate natural resources like clean air and water, and large numbers of us understand the importance of topsoil, of forests and fisheries, and of readily accessible high-grade mineral ores and fossil fuels.

Many also take for granted the value of artifacts like houses, machinery, and other intentional results of human labor. In our era, people are increasingly reliant upon information resources like books, film, computers, and telecommunications systems.


Elements of the environment which we perceive as obstacles to our satisfaction we label hazards. We have enjoyed great success in learning to escape natural hazards, like the many predators and parasites which plagued our ancestors but pose little threat today.

At the same time, we face a growing list of hazards which are of our own making. These include various intended and unintended outputs of our own activities, from explosives to smog. We can also generate hazard by communicating misinformation, either genetically or behaviorally.


Many people can find good reason to view information as the paramount factor of the four we have discussed.

With information we determine our numbers. Biologists agree that we are genetically informed to reproduce to maximum potential. From experience we may learn to make many children, or to make few, and techniques for doing whichever we choose.

With information we may recognize resource and exploit it, and we may identify hazard and escape it.

Perhaps most critically, with information we alter and augment information.

Learning is the primary means we currently possess to modify our information. The methods by which we learn, and the choices we make with respect to what we learn may be among the most important aspects of our lives.

Unlike the tens of thousands of generations of our ancestors who were intimate with a natural world, we live in an environment which bears the human imprint in its every corner. We learn primarily from each other, either directly or through the symbolic content of the words and other artificial elements in which we are immersed.

If we define culture in general terms, as information transferred among individuals of the same species by teaching and learning, then we may view it as a double-edged sword. With it we may learn from others' mistakes, but we also may learn their mistakes.

Relying on a system of human understanding increasingly self-contained and insulated from natural phenomena, we have exacerbated the risk that we may become part of a mass delusion, unaware of the laws of nature, though still subject to them.

By repeatedly questioning, testing, altering, and communicating our understanding about what we want and how we may secure it, we may contribute to the evolution of a more reliable human culture.

Millions of us enjoy access to information more accurate than that by which we live. We have opportunity to examine our lives and to replace the beliefs we acquired uncritically, often by accident of birth, with ideas better-suited to successful adaptation.

To shed illusion we will question 'conventional wisdom.' We will affirm our own and others' ability to learn and to change. In doing so we will teach these behaviors to our neighbors and friends, for inevitably we teach what we are.


Millions of people over many generations have developed the laws of physical science. In the process we have confirmed that these laws apply without exception to the entire known universe, including all of the living world. Whether breathing, conducting business, or planning a community, each of us acts within limits defined by fundamental scientific principles.

To begin to learn an ecological perspective, we will become acquainted with the First and Second Laws of Thermodynamics. With even this rudimentary skeleton of scientific understanding, we will be able to shed new light on our world and ourselves.


The First Law, often called the Conservation Law, states that matterenergy can be neither created nor destroyed, only converted from one form to another. Implicit in the First Law is the inaccuracy of human claims to 'produce' food, shelter, clothing, or any other material entity. We convert these from other forms.

When we regard manufacturing as 'conversion' we may more readily take cognizance of the full range of inputs and outputs, and of the many antecedent and consequent conversions of the cycles and flows in which a manufacturing process is embedded. As we cultivate such awareness, we are likely also to realize that although we may label some outputs 'by-products' or 'waste,' these almost invariably wind up somewhere other than 'away.'

Thinking in terms of conversion, we can place an imaginary bubble around a location or process, and observe the quality and quantity of flows through that membrane. If we contrast the ecological description we generate from such an exercise with an economic description of the same process, we discover that the former is more complete. By including reference to previously ignored matterenergy flows on the income statements and balance sheets of households, businesses, and municipalities we may make these more useful and accurate representations.


The Second Law, sometimes called the Entropy Law, states that every conversion results in net degradation. Though matterenergy quality measured in thermodynamic terms is but one yardstick by which we may judge value, many people familiar with the Second Law regard it a sobering reminder of boundaries within which we necessarily live. Viewed in the light of the Second Law, the growth of what we call GNP, which is really a partial measure of Gross National Conversion, may be more destructive than beneficial.


Sustained life on Earth is possible because there are flows of energy into the biosphere which can offset the degradations resulting from the matterenergy conversions on which life depends. Our energy income includes geothermal heat generated by radioactive decay within our planet, gravitational energy from the moon, radiation from distant stars, and light energy from the sun.

For billions of years, immense planetary cycles of carbon, oxygen, phosphorus, nitrogen, water, and other components of life have been energized by the daily ration of sunlight intercepted by the Earth. Wind, ocean currents, and the cycle of evaporation and precipitation are all sun-driven processes which we have diverted to human use. By doing so we have negatively altered the conditions of life for many other species and for some people as well.

By capturing a small amount of the sunlight which reaches the Earth, and converting it to the energy of chemical bonds, photosynthetic organisms provide the input by which the preponderance of known life on this planet is maintained. The growth of pasture grasses, of the cow that grazes them, and of the child who drinks the cow's milk, are powered by sunlight. In effect, degradation of the sun is the price of life on Earth. We and our domesticated animals now claim nearly half of the products of terrestrial photosynthesis, leaving many other animals with too little to survive.

We also have tapped the energy of ancient sunlight, converted by plants and stored in their fossilized remains, to augment contemporary rates of conversion. In the process we have precipitously reintroduced to the biosphere matterenergy which was withdrawn and sequestered over millions of years. The unwanted impacts of fossil fuel burning include growing instability of climate.

The qualities of life and those of the environment are like lock and key. Changes to one require changes to the other if they are to function together. Inevitably our reckoning of the extent and type of change we bring by our conversions is incomplete. And however benign our intention, we pose adaptive challenge for ourselves and for other life each time we initiate environmental change. By opening a sufficient gap between the pattern of a life-form and that of the environment we kill the individual or extinguish the species.

With our environmental impacts we are driving an accelerating extinction of species certainly unlike any which has occurred for more than fifty million years, and possibly unprecedented in Earth history. Conserving diversity in the biological portfolio may well be essential to secure the stream of unearned income from nature on which we have relied to date for our own well-being.

To restablize the biosphere we will learn to live within its income and within the limits of its resilience. Almost certainly we will reduce our numbers and our matterenergy conversions, and just as surely we will rely more heavily upon technologies by which we integrate with natural cycles more and disrupt them less.


Ecology has been termed 'the subversive science' because people who apply it to questions of value almost always arrive at conclusions which are in one or another way incompatible with central tenets of long-standing political, economic, and religious traditions. Despite this unsettling quality, most who become familiar with an ecological approach find its advantages too great to surrender.


If we undertake an ecological search for 'good' around which to build a positive vision of community, we might regard life and ask, "What if anything is universally valued?" One answer for which we find ample evidence is: "That which enables survival, reproduction, and evolution." Taking even a few moments to observe the living world, we can confirm that most organisms devote virtually all of their lives to feeding and breeding. That all life is participating in a vast evolutionary process is supported by a fossil record now 3.5 billion years long.

The human species is part of this pattern. Most of us behave as if intending to secure our own and our children's lives. Though we are surrounded by exhortations to put our attention elsewhere we continue to see 'job and family' at the core of our existence.


Humans have another side. From early childhood we are aware of the inevitable death of individuals. Those with even a modest knowledge of evolutionary biology realize that only a tiny fraction of all species which ever inhabited the Earth survive to this day. Astronomers have witnessed the appearance and dissolution of stars very probably surrounded by planetary systems much like our own.

If we live tenaciously clinging to ideas of individual survival, offspring carrying our genes and culture into the future, and life on Earth evolving forever, we are likely doomed to a sense of failure. All these processes will almost certainly come to an end. If we are to enjoy them while they last, rather than struggle to give them a permanence they lack, we will learn to accept their transience. In virtually all human societies we see evidence of activities reflecting an awareness of the value of transcending preoccupation with material life.


With these observations of what living things, including nearly all people, actually do, we have marshalled evidence that humans share a common purpose: to balance our desires to survive, to reproduce, and to evolve with acceptance of the inevitability of our own death, our species' extinction, and the end of life on Earth.


Thoreau is reported to have once remarked to someone, "What you are speaks so loudly that I cannot hear a word you say." Most of us communicate with far more people by the being that we exhibit in our everyday actions than we do with our words. The resources and labor we command in the service of our own desires, the direct interactions with the environment by which we satisfy those desires ourselves, and the ways in which we respond to others' requests and commands, and act to satisfy them are among the primary modes by which we define self and community.

To explore our own values as we express them in our lives, we might begin by considering some broad and near-universal categories of behavior. What do we eat? Where do we live? How do we furnish it? What do we wear? How do we groom?

What transportation do we use? What recreation or entertainment do we pursue? What government services do we rely upon? What education, communication, and medical services? Who cooks or cleans where we live? Who cares for children?

What goods or services do we provide in our work? How are these related to the world we want for children born today?

With what purposes do we live as we do? In what relationship do we stand to those who provide for our needs? To those for whom we provide?

What do we imagine to be the consequences of dramatic change in our responses to any of the above questions? By what might we be motivated to alter them? To save our own life? A child? A close friend? A thousand peasants? An endangered species of mammal?

What might someone who views a videotape of our days and nights, or a printout of our thoughts and feelings, say we value? How may we better reflect our most deeply held values in every aspect of living? To what extent shall we engage in cooperative activity to enable mutual satisfaction of common purposes?

With our responses to questions like these we lay the foundation on which we plan and act to determine our own character and to influence the quality of any community of which we are a part.


The Earth ecosystem is increasingly a mirror of human consciousness, and ours is a consciousness of plunging ignorantly into unexplored territory. Each of us can point to many instances of unexpected damage attributable to people's failure to question thoroughly before acting.

Here in the San Francisco Bay Area we have contaminated the air, the soil, the water, and the wildlife. With phenomena like destruction of stratospheric ozone by our release of CFC's, we have demonstrated that our impacts are truly global.

We make our willingness to leave the future to chance more dangerous as we augment the size, speed, and novelty of our undertakings. Our forebears might err in fruit-gathering with little consequence. By our own mistakes in nuclear power plant design we can induce cataclysm.


Earlier in this writing we noted that we might conduct a simple ecological analysis in terms of four factors: human numbers and information, and environmental resources and hazards. Now we will assess recent trends in each.

We are increasing the number of people, already at an all-time high, at a still-accelerating pace. Demographers currently anticipate a population at least half again, and perhaps twice as large as today's by the middle of the next century.

Though researchers are steadily accumulating new techniques by which to manipulate the material world, much of humanity is experiencing rapid and rampant information erosion. Infants born genetically defective or damaged in utero are increasingly numerous. We are causing additional degeneracy by willful or inadvertent exposure to toxicity. Hundreds of millions of children who live on the edge of death are growing up illiterate because their families lack the current surplus requisite to literacy education. Billions are embracing dogma of every stripe, from nationalism to religious fanaticism, from astrology to political and economic ideology.

We are depleting resource and generating hazard at peak and still-rising levels. Declining fishery, farmland, forest, and groundwater resources are typical of our wasting of nature. Crumbling roads and bridges exemplify our analogous degradation of artifact. Unstable climate, pesticide-resistant insects, weapons of mass destruction, and manufactured toxic substances all bear witness to how we are making both the natural and artificial environments more dangerous.


All of these phenomena are in turn reflected in our declining ability to further our common values. Survival is beyond the reach of the tens of millions who each year starve, or die from preventable or curable disease for want of understanding or treatment. Life expectancies, on the rise for more than a century, have recently turned down among large populations as distinct and unrelated as African-Americans and Russians.

Compromised by the myriad stresses of coping with environmental deterioration and population increase, both men and women in the United States are less fertile today than a decade ago. Parents lacking capacity to carry a well-developed fetus to term or to rear a healthy child are reproducing disproportionately large numbers of offspring.

Damaged children are absorbing parental and societal resource without affording much assurance that we are satisfying either individual reproductive objectives or common evolutionary goals. As we ignore science for dogma, we further dim our evolutionary prospects, raising the spectre of human extinction in our own time.

We are equally unsatisfied in our desires to feel connected to each other and the Earth. At levels of social organization from family to nation we may observe increasing alienation and conflict. Divorce, runaway children, homelessness, crime, terrorism, rioting, and war are becoming commonplace. More and more people, unable to eke out a living from depleted rural landscapes, crowd into the unnatural realm of cities. Diminished in our capacity to know and appreciate nature, urbanites take refuge in alternative realities, like television and video games.

Many born and raised in the United States are finding the material and social conditions of life to be more difficult than we had expected. Frustrated, we are looking for some way to salvage our dreams. Thoughtful people are awakening to the likely impossibility of this task, and are adjusting ambitions accordingly.


To continue as we are is to suffer. Many positive qualities of human population and environment are in downtrends. A host of negative qualities are in uptrends. The good news is that humans are driving these phenomena, and are apparently doing so to a great extent on the basis of information which we may be able to supplant with something more conducive to our own and our children's well-being. A kernel issue of our times is: "How may we transform the selves we see mirrored in global ecological reality into beings whose reflected image we will find more pleasing?"

Will we replace the trends to bigger, faster, more novel manipulation, to rigid belief and uncharitable blame, by a movement to more cautious and restrained action based in skepticism, observation, reason, and cooperation? Each of us provides a partial answer by how we live.


Implicit in patterns of human settlement on the Earth is a range of possibilities for our numbers and information, and for rates and types of resource depletion and hazard generation. Because our ability to fulfill our common desires depends upon the status and trends of these factors, the geographical distribution of humans serves as both a foundation and a limit for our lives.


Generally speaking, people can meet basic needs with matterenergy conversion of least disruptive quality and quantity where we and our artifacts are sparse enough to be sustained by local flows of renewable resource. The requisites of such sustenance vary from place to place, but if we think just in terms of food and warmth in order to grasp the overall concept, we can say that even in favorable locations, Earth will only rarely support more than about five to ten people per acre.

At densities higher than these, we require exponentially increasing matterenergy conversion to import resource and export waste. Furthermore, as we extend such densities over larger contiguous areas, we require yet another exponential increase in per capita conversion, again as a result of transportation requirements.

As we take further steps into urbanization, we rely upon additional technologies and more complex forms of social organization. Though each increment brings opportunities, each is also accompanied by greater requirements for matterenergy conversion.

Today the residents of a typical urban household in a major city convert matterenergy at a rate ten or even a hundred times as great as that of a rural peasant family. Though much of this difference may be attributable to continuing application of inefficient, outdated technology, or may reflect real discrepancies in quality of life, some part is due simply to the unavoidable consequences of extensive concentration of population and artifact.

As we move towards the twenty-first century people are weighing the benefits of such concentrations against their costs. For each additional person, house, or business we might well ask, "What location will afford maximum satisfaction per unit of conversion?"


Let's assume that well-established trends will persist, at least for a time. With a combination of population growth, environmental destruction, social dislocation, and information shortfall we are plunging towards a leveling of human conditions stemming more from inability to maintain standards of decency than from newly found capacity to extend them.

By relying upon large-scale, complex technologies and organizations, we have increased our vulnerability. By the global nature of the phenomena with which we are undermining the quality of our lives we have made escape impossible. Many of us are seeing more clearly the futility of attempting to maintain familiar privilege.

In the face of these changes, current patterns of matterenergy conversion are proving less tenable, as are the types of human settlement we have built with them. We are being compelled to amortize dysfunctional capital assets, of which urban artifacts are prime examples, much more quickly than we had anticipated.


What will we discover to be necessary to enable each generation to live as well as that which precedes it? Will we reduce the human population, reduce the quantity and alter the quality of our matterenergy conversions, and inform these actions with widespread respect for ecological principle?

As we feel the full consequences of dense and extensive concentration of people and artifact, a growing number of us are finding compelling reason to deconstruct megalopolises. Carefully premeditated, this can be a regenerative transformation. Still we hear calls to 'save the cities' by net additions of population or artifact to major metropolitan areas. Though often couched in terms of social justice, the actions advocated by those who utter such appeals are poor means to further this end. With ecological analysis we can see that we may secure greater satisfaction of our common interests by investing in places less densely and extensively settled.

By what incentives may we end the squandering of dwindling resource on re-creation of anachronistic form? How may we better husband that which is currently in place, abandoning its least useful elements, and converting others to adjust both denseness and extensiveness of settlement to levels which rely upon matterenergy conversions of kinds and at rates which can be sustained for decades or longer?

By redefining our relationships to each other and to the rest of the world with reference to ethical and economic values which we have thoroughly informed with ecological understanding, we may halt destructive growth, and accomplish an orderly transition to a society in which we value quality over surfeit. By more rapidly aligning the laws of political economy with natural law, and further accelerating the acquisition of ecological awareness by market participants, we may slow or even arrest the cascade of negative impacts, many irreversible, which has characterized our recent past.

Just as we are paying bounties to retire gas-guzzling, pollutant-spewing older cars, so are we beginning to provide economic incentives to supplant urban artifact with nature, and to reshape it to more benign form. Tree planters and caretakers in the burgeoning 'urban forestry' movement bear witness to this trend.

That we have to date responded to environmental imperatives less rapidly and dramatically with urban design than with auto design is an indication of the greater 'momentum' of the former. The useful life, sunk costs, and resource impacts of buildings and pavement are typically at least one, and often several, orders of magnitude greater than those of an automobile.

In our era of accelerating change we may view the greater costs and permanence of urban design elements as incentives to look far and carefully into the future when we contemplate reshaping our settlements. What we construct now may endure for decades. We will be prudent to take accurate measure of existing trends, and to build with an eye to flexibility in the face of growing volatility.

In places with less artifact and fewer people per unit of land we usually find greater opportunity for reintegration with nature, and for fulfillment of human needs using local resources. Though we may feel tempted to crowd artifact and population into major metropolises in order to reduce land prices per unit of floor space, people have consistently found the ecological costs of such action greater than both their economic price and their ecological benefits.

We know this in our bones. That is why so many of us vacation and retire in the countryside. But to enjoy the present or accumulated fruits of a city career in the countryside or anywhere else, we will respect natural law and maintain the integrity of Earth systems.

What if our assumptions are wrong, if we shrink the human population, or discover new resources or information to alter the ecological equation? In these circumstances, we may enjoy the prospect of a long and happy future in which to resume our current course, assuming that we prefer it. If, alternatively, our assumptions are correct, but we continue concentrating people and artifact at high densities over large areas, we can expect to work harder and harder for less and less.


Many of us have planned for a household. Doing so is in many ways analogous to planning for any other community. We begin by locating the boundaries of the planning area. Then we inventory its contents, assess the flows through it, and examine the social relations among its inhabitants, and between them and other people.

For a household we customarily draw the boundary at the walls and doors of a unit in a multi-unit building, or at the property line for a detached home.

How many human occupants are there? What is their expected tenure? What services do they offer and command? Are there pets, wildlife, microbes, plants, machines, appliances, furniture, books, clothing? What else?

What are the flows through the household? When and how do people come and go? What about other living things? Air? Water? Cars? Bikes? Food? Sewage? Mail? Electricity? Gas? Radio and television? Sunlight? Phone? Fax? Sound? Refuse? Furnishings?

From the terms on which occupancy is shared, what may we conclude about occupants' individual values and desires, and the power with which each advances them? And what do the stocks and flows of the household, and the aspirations of the residents reveal of the underlying power relationships between household members and the society beyond?

Analyzing the household in terms of all of these factors, we establish a foundation for planning. On the basis of a similar analysis we may begin to plan for a neighborhood, a municipality, a bioregion, a nation, or even the planet.

Most of us have planned largely in terms of money values. The global economy is undergoing wrenching disruptions as people bring monetary representations of wealth into accord with ecological reality.

When we plan changes which may endure for generations, like buildings, pavement, or utilities systems, we are prudent to anticipate the further internalization of real costs which we are effecting as we express ecological understanding in the patterns of our lives, and in the structure and processes of the marketplace. In this way we may make the necessary and inevitable conformation of belief to fact a process by which we reinforce our actions and enhance our ability to meet our objectives.

With an ecological approach to planning we emphasize thorough analysis, and enlist all participants in a search for accurate understanding. Once we have made our analysis sufficiently robust, we may consider alternative visions for the future in the light of natural laws which define the limits of the realizable, and of common values which are the foundation for human community. As we move forward, we can repeatedly apply our analysis to evaluate proposed goals, objectives, policies and programs according to reliable, coherent, and consistent criteria.

By coming to a planning process full of questions, ready to set aside preconceptions, and with an unequivocal sense of accountability to all whose lives we influence by our participation, we may improve the likelihood that our actions will bring community benefit. Determined to wield whatever power we possess to secure mutual advantage, we may plan more effectively towards the well-being of self, humankind, and the ecosystem on which we depend.


In these pages we sketched an ecological approach to land planning. We identified four primary factors in the ecological function, and explained the primacy of information and the importance of learning. Next we outlined two fundamental natural laws and discussed their implications for people.We showed how nearly invariant patterns in nature and in society support an assertion that humans share common values, and we emphasized that our everyday lives are the vehicles by which we express our values.

Then we analyzed the current human condition in the light of our common values, and concluded that accelerated learning which reaches to the very roots of our understanding may well be essential to our satisfaction. We applied the principles and methods of ecology to examine human settlement patterns, and illustrated how we may use an ecological approach to plan more effectively for any community of which we are a part.

Most of us formed our expectations in an environment more benign than today's, yet we appear destined to live, at least for awhile, in one ever more difficult. Our opportunities lie to a great extent in abandoning the ways of being, many long-practiced and deeply-embedded, by which we have arrived in our current predicament.

Though some may find this prospect daunting, others will see in it the possibility for human evolution far more positive than any we might attain by persisting on our current path.