Chapter Excerpt

1

Questions

I have many attitudes to technology. I use it and take it for granted. I enjoy it and occasionally am frustrated by it. And I am vaguely suspicious of what it is doing to our lives. But I am also caught up by a wonderment at technology, a wonderment at what we humans have created. Recently researchers at the University of Pittsburgh developed a technology that allows a monkey with tiny electrodes implanted in its brain to control a mechanical arm. The monkey does this not by twitching or blinking or making any slight movement, but by using its thoughts alone.

The workings behind this technology are not enormously complicated. They consist of standard parts from the electronics and robotics repertoires: circuits that detect the monkey's brain signals, processors and mechanical actuators that translate these into mechanical motions, other circuits that feed back a sense of touch to the monkey's brain. The real accomplishment has been to understand the neural circuits that "intend" motion, and tap into these appropriately so that the monkey can use these circuits to move the arm. The technology has obvious promise for impaired people. But that is not what causes me wonder. I wonder that we can put together circuits and mechanical linkages -- in the end, pieces of silicon and copper wiring, strips of metal and small gears -- so that machinery moves in response to thought and to thought alone.

I wonder at other things we can do. We put together pieces of metal alloy and fossil fuel so that we hurtle through the sky at close to the speed of sound; we organize tiny signals from the spins of atomic nuclei to make images of the neural circuits inside our brains; we organize biological objects -- enzymes -- to snip tiny slivers of molecules from DNA and paste them into bacterial cells. Two or three centuries ago we could not have imagined these powers. And I find them, and how we have come by them, a wonder.

Most of us do not stop to ponder technology. It is something we find useful but that fades to the background of our world. Yet -- and this is another source of wonder for me -- this thing that fades to the background of our world also creates that world. It creates the realm our lives inhabit. If you woke some morning and found that by some odd magic the technologies that have appeared in the last six hundred years had suddenly vanished: if you found that your toilet and stove and computer and automobile had disappeared, and along with these, steel and concrete buildings, mass production, public hygiene, the steam engine, modern agriculture, the joint stock company, and the printing press, you would find that our modern world had also disappeared. You -- or we, if this strange happening befell all of us -- would still be left with our ideas and culture, and with our children and spouses. And we would still have technologies. We would have water mills, and foundries, and oxcarts; and coarse linens, and hooded cloaks, and sophisticated techniques for building cathedrals. But we would once again be medieval.

Technology is what separates us from the Middle Ages; indeed it is what separates us from the way we lived 50,000 or more years ago. More than anything else technology creates our world. It creates our wealth, our economy, our very way of being.

What then is this thing of such importance? What is technology in its nature, in its deepest essence? Where does it come from? And how does it evolve?

These are the questions I will ask in this book.

Maybe we can simply accept technology and not concern ourselves much with the deeper questions behind it. But I believe -- in fact I believe fervently -- that it is important to understand what technology is and how it comes to be. This is not just because technology creates much of our world. It is because technology at this stage in our history weighs on us, weighs on our concerns, whether we pay attention to it or not. Certainly technology has enabled our children to survive where formerly they might have died; it has prolonged our own lives and made them a great deal more comfortable than those of our ancestors just two or three centuries ago; it has brought us prosperity. But it has also brought us a profound unease.

This unease does not just come from a fear that technologies cause new problems for every problem they solve. It wells up also from a deeper and more unconscious source. We place our hopes in technology. We hope in technology to make our lives better, to solve our problems, to get us out of predicaments, to provide the future we want for ourselves and our children. Yet, as humans, we are attuned not to this thing we hope in -- not to technology -- but to something different. We are attuned in the deepest parts of our being to nature, to our original surroundings and our original condition as humankind. We have a familiarity with nature, a reliance on it that comes from three million years of at-homeness with it. We trust nature. When we happen upon a technology such as stemcell regenerative therapy, we experience hope. But we also immediately ask how natural this technology is. And so we are caught between two huge and unconscious forces: Our deepest hope as humans lies in technology; but our deepest trust lies in nature. These forces are like tectonic plates grinding inexorably into each other in one long, slow collision.

The collision is not new, but more than anything else it is defining our era. Technology is steadily creating the dominant issues and upheavals of our time. We are moving from an era where machines enhanced the natural -- speeded our movements, saved our sweat, stitched our clothing -- to one that brings in technologies that resemble or replace the natural -- genetic engineering, artificial intelligence, medical devices implanted in our bodies. As we learn to use these technologies, we are moving from using nature to intervening directly within nature. And so the story of this century will be about the clash between what technology offers and what we feel comfortable with. No one claims that the nature and workings of technology are simple; there is no reason to think they are simpler than the nature and workings of the economy or of the law. But they are determining for our future and our anxieties about it.

This book is not about the benefits or evils of technology, there are other books that look at these. It is an attempt to understand this thing that creates so much of our world and causes us so much unconscious unease.

And this brings us back to the same questions. What is technology? What is it in the deepest sense of its nature? What are its properties and principles? Where does it come from -- how does it come into being? How does it develop? And how does it evolve?

Missing: An "-ology" of Technology

One good place to start is to ask what we really know about technology. The reader might expect the answer here to be straightforward, but actually it is not. In fact it is almost paradoxical: we know a great deal about technology and we know little. We know a great deal about technologies in their individual sense, but much less about technology in the way of general understandings. We know all the particularities about the individual methods and practices and machinery we use -- or at least some people, the designers of these, do. We know every step in the production of a computer microprocessor, and every part of the processor, and every part of every part. We know exactly how the processor operates, and all the pathways of the electrons inside it. And we know how the processor fits with the other components in a computer, how it interfaces with the BIOS chip and the interrupt controller. We know exactly these things -- exactly what lies within each technology -- because we have placed them all there in all their detail. Technology in fact is one of the most completely known parts of the human experience. Yet of its essence -- the deep nature of its being -- we know little.

This sort of contrast between known content and less-known principles is not rare. Around two centuries ago, in the time of the French zoologist Georges Cuvier, biology (or natural history as it was then called) was a vast body of knowledge on individual species and their comparative anatomy and their interrelations. "Today," he said, writing in 1798, "comparative anatomy has reached such a point of perfection that, after inspecting a single bone, one can often determine the class, and sometimes even the genus of the animal to which it belonged." Cuvier was only slightly exaggerating. Naturalists did have detailed knowledge, and they were deeply aware of the family relationships among animals. But they had few principles to hold all this knowledge together. They had no clear idea of how animals had come to be; no mechanism by which evolution -- if it existed -- could work; no obvious idea of whether animals could modify their parts or how this could happen. All this came later, as principles were found.

We are in the same position with technology. We have detailed studies about the history of individual technologies and how they came into being. We have analyses of the design process; excellent work on how economic factors influence the design of technologies, how the adoption process works, and how technologies diffuse in the economy. We have analyses of how society shapes technology, and of how technology shapes society. And we have meditations on the meaning of technology, and on technology as determining -- or not determining -- human history. But we have no agreement on what the word "technology" means, no overall theory of how technologies come into being, no deep understanding of what "innovation" consists of, and no theory of evolution for technology. Missing is a set of overall principles that would give the subject a logical structure, the sort of structure that would help fill these gaps.

Missing, in other words, is a theory of technology -- an "-ology" of technology.

There is no clear reason why this is so. But I strongly suspect that because technology stands in the shadow of its more prestigious sister, science, we honor it less -- and therefore study it less. And I suspect that because we feel technology to be the cause of much disharmony in our world, at some unconscious level we feel it to be intellectually distasteful -- unworthy perhaps of deep study. We also feel vaguely that because we have created technology, we already understand it.

And there is another reason. The people who have thought hardest about the general questions of technology have mostly been social scientists and philosophers, and understandably they have tended to view technology from the outside as stand-alone objects. There is the steam engine, the railroad, the Bessemer process, the dynamo, and each of these is a boxed-up object with no visible insides -- a black box, to use economic historian Nathan Rosenberg's term. Seeing technologies this way, from the outside, works well enough if we want to know how technologies enter the economy and spread within it. But it does not work well for the fundamental questions that interest us. It is like viewing the animal kingdom as a collection of separate black-boxed species: lemurs, macaques, zebras, platypuses. With no obvious relation between these and no inside anatomies to compare, it would be difficult to see how they are related as species, how they originate in the first place, and how they subsequently evolve. So it is with technologies. If we want to know how they relate to each other, and how they originate and subsequently evolve, we need to open them up and look at their inside anatomies.

I want to be fair in what I say here. Social scientists are aware that technologies have inside components, and in many cases are well aware of how these work together to produce the technology. And some historians have opened up technologies to look in detail at how they originated and changed over time. But most of this "inside thinking" concerns itself with particular technologies -- radio, radar, the Internet -- and not with technologies in a general sense. Things might have been different if engineers had been the main thinkers about technology; they naturally see technologies from the inside. I once asked the distinguished technologist Walter Vincenti why so few engineers had attempted to lay down a theoretical foundation for their field. "Engineers," he told me, "like problems they can solve."

Evolution in Technology

One of the problems I want to solve, certainly one of the deeper questions about technology, is how it evolves. Or, I should say, whether it evolves, because it is not clear without argument that technology evolves at all. The word "evolution" has two general meanings. One is the gradual development of something, as with the "evolution" of ballet or the English madrigal. I will call this evolution in the narrow sense, or more usually "development." The other is the process by which all objects of some class are related by ties of common descent from the collection of earlier objects. This is evolution in its full sense, and it is what I will mean by evolution.

For me, how technology evolves is the central question in technology. Why do I believe this? Without evolution -- without a sense of common relatedness -- technologies seem to be born independently and improve independently. Each must come from some unexplained mental process, some form of "creativity" or "thinking outside the box" that brings it into existence and separately develops it. With evolution (if we can find how it works), new technologies would be birthed in some precise way from previous ones, albeit with considerable mental midwifing, and develop through some understood process of adaptation. In other words, if we could understand evolution, we could understand that most mysterious of processes: innovation.

The idea of evolution in technology is by no means new. Barely four years after Darwin's Origin of Species, Samuel Butler was calling for a theory of the "mechanical kingdom" that would explain "that part among machines which natural selection has performed in the animal and vegetable kingdoms...." His essay, "Darwin Among the Machines," is full of the enthusiasms of the time: "[t]here is nothing which our infatuated race would desire more than to see a fertile union between two steam engines; it is true that machinery is even at this present time employed in begetting machinery, in becoming the parent of machines often after its own kind, but the days of flirtation, courtship, and matrimony appear to be very remote." This, of course, is hyperbole. Still, if I take the essay seriously, I cannot avoid feeling Butler is trying to shoehorn technology into a framework -- Darwin's biological evolution -- that might not be appropriate for it.

What is clear from the historical record is that modern versions of certain particular technologies do descend from earlier forms. About seventy years after Butler, the sociologist S. Colum Gilfillan traced the descent of the ship from the dugout canoe to the sailing ship to the modern steamship of his day. Gilfillan was a member of a small American school of historians and sociologists that was deeply interested in technology and invention in the 1920s and 30s. And he was knowledgeable about ships; he had been curator of shipping for Chicago's Museum of Science and Industry. In 1935 he traced in historical detail how each of the "inventions" of planking, ribbing, fastenings, keels, lateen sails, and square sails came about (he devotes four pages to the origins of the gaff sail alone); how these gradually transformed the most primitive floating objects into the sailing ship; and how further inventions metamorphosed the sailing ship into the modern steamship. This is not evolution in its full sense. It is "evolution" in the narrow sense of gradual development: the descent of form. What Gilfillan showed is that for some technologies, certainly for ships, we can trace a detailed line of descent.

For a full theory of evolution we would need something more. We would need an argument that all technologies, not just some, are descended from earlier technologies, and an explicit mechanism by which this happens. Attempts to provide such an argument have been few, and unsuccesful. Most, like Butler's, have been more proposals than theories, and all base their reasoning squarely on Darwin's. The central idea works this way. A given technology, the railroad locomotive, say, exists at a particular time in many variants. This is because it has different purposes to fulfill, different environments to operate in (different "habitats" to adapt to, if you like), and different designers who use different ideas. From these variations, some perform better and are selected for further use and development; they pass on their small differences to future designs. We can then follow Darwin and say that "it is the steady accumulation, through natural selection, of such differences, when beneficial to the individual, that gives rise to all the more important modifications of structure." In this way technology evolves.

The argument sounds reasonable, but it quickly runs into a difficulty. Some technologies -- the laser, the jet engine, radar, the Quicksort computer algorithm, the railroad locomotive itself -- just appear, or at least they seem to just appear, and unlike novel biological species, they are not versions of earlier objects. The jet engine is not a variation of the internal combustion engine or anything else that preceded it, and it did not come into being by the steady accumulation of small changes in its predecessors. So explaining "novelty," meaning abrupt radical novelty, becomes a major obstacle for technology evolutionists. The appearance of radically novel technologies -- the equivalent of novel species in biology -- cannot be accounted for.

One way out, a rather extreme one, is to lean harder on Darwin and say that if different designers bring forth different variants of a technology, some of these variants and the ideas behind them may be radical. Change can therefore be radical and abrupt, as well as gradual. This sounds plausible enough, but if you look into what it would require in practice for any radical innovation it does not stand up. Radar "descends" from radio. But you can vary 1930s radio circuits all you like and as radically as you like and you will never get radar. Even if you vary ideas about radio circuits all you like you will still not get radar. Radar requires a different principle than radio.

I do not want to dismiss variation and selection in technology. Certainly technologies exist in multiple versions and certainly superior performers are selected, so that later forms can indeed descend in this way from earlier ones. But when we face the key question of how radically novel technologies originate -- the equivalent of Darwin's question of how novel species originate in biology -- we get stymied. Darwin's mechanism does not work.

Combinatorial Evolution

There is a way toward understanding how technology evolves, but to get there we need to shift our thinking. What we should really be looking for is not how Darwin's mechanism should work to produce radical novelty in technology, but how "heredity" might work in technology. If evolution in its fullest sense holds in technology, then all technologies, including novel ones, must descend in some way from the technologies that preceded them. This means they must link with -- be "sired" by -- certain technologies that preceded them. In other words, evolution requires a mechanism of "heredity," some detailed connection that links the present to the past. From the outside it is impossible to see this mechanism -- looked at as a black-boxed device, it is hard to say how the laser has come into being from previous technologies.

What if we looked inside technologies? Would we see anything that would tell us how novelty works in technology? Would we see anything that could yield a proper theory of evolution for technology?

If you open up a jet engine (or aircraft gas turbine powerplant, to give it its professional name), you find components inside -- compressors, turbines, combustion systems. If you open up other technologies that existed before it, you find some of the same components. Inside electrical power generating systems of the early twentieth century were turbines and combustion systems; inside industrial blower units of the same period were compressors. Technologies inherit parts from the technologies that preceded them, so putting such parts together -- combining them -- must have a great deal to do with how technologies come into being. This makes the abrupt appearance of radically novel technologies suddenly seem much less abrupt. Technologies somehow must come into being as fresh combinations of what already exists.

So far, this is only a hint of something we can use to explain novelty. But built up properly it will be central to my argument. Novel technologies must somehow arise by combination of existing technologies.

Actually, this idea, like evolution itself, is by no means new. It has been mooted about by various people for well over 100 years, among them the Austrian economist Joseph Schumpeter. In 1910 Schumpeter was twenty-seven, and he was concerned not directly with combination and technology but with combination in the economy. "To produce," he said, "means to combine materials and forces within our reach.... To produce other things, or the same things by a different method, means to combine these materials and forces differently." Change in the economy arose from "new combinations of productive means." In modern language we would say it arose from new combinations of technology.

Schumpeter had come to this idea because he had been asking a seemingly simple question: how does an economy develop? (In modern language we would say, how does it change structurally?) External factors of course can change an economy: if it discovers a new source of raw materials, or starts to trade with a new foreign partner, or opens up new territories, its structure can change. But Schumpeter was asking whether an economy could change itself without external factors -- purely from within -- and if so how. The prevailing doctrine of the time, equilibrium economics, held that it could not. Without outside disturbances, the economy would settle into a static pattern or equilibrium, fluctuate around this, and stay there. Schumpeter, however, realized there was "a source of energy within the economic system which would of itself disrupt any equilibrium that might be attained." That source was combination. The economy continually created the new by combining the old, and in doing so it disrupted itself constantly from within.

Schumpeter's book did not appear in English until 1934, and by then other people in the 1920s and 30s had come to the same conclusion: combination drove change -- or at least the innovation of technology. Invention, said historian Abbott Payson Usher in 1929 -- another member of the American school -- proceeds from "the constructive assimilation of pre-existing elements into new syntheses." Gilfillan himself put it more succinctly: an invention is a "new combination of prior art." After that the idea drifted, occasionally mentioned but not much invoked, in part because nobody -- not Schumpeter, not Usher, not Gilfillan, nor anyone else -- explained how such combination could bring forth a new invention. It is easy enough to say that the jet engine is a combination of parts available to its inventors, Frank Whittle and Hans von Ohain, but not easy to explain how such combination takes place in the minds of a Whittle or von Ohain.

Combination at least suggests a way by which novelty arises in technology. But this merely links individual novel technologies back to particular technologies that existed before. It does not yet give us a sense of the whole of technology building up from what went before. For that we need to add a second piece to the argument. If new technologies are indeed combinations of previous ones, then the stock of existing technologies must somehow provide the parts for combination. So the very cumulation of earlier technologies begets further cumulation.

This idea has a history too. One of Schumpeter's near contemporaries, the American William Fielding Ogburn, pointed this out in 1922. Ogburn was a sociologist, and again very much a member of the American school. He was fascinated by what generated social change (or in his language, change in material culture). And like Schumpeter he saw the combination of previous technologies -- invention -- as the source of change. But he also saw something else: that inventions built cumulatively from earlier inventions. "It would seem that the larger the equipment of material culture the greater the number of inventions. The more there is to invent with, the greater will be the number of inventions." This explained why more "primitive" societies could not invent our modern technologies; they did not possess the necessary ingredients and knowledge of how to work with them. "The street car could not have been invented from the material culture existing at the last glacial period. The discovery of the power of steam and the mechanical technology existing at the time made possible a large number of inventions." The insight here is marvelous. But sadly, it ends there. Ogburn does not use it to construct any theory of technology or of its evolution, which he easily could have.

If we put these two pieces together, that novel technologies arise by combination of existing technologies and that (therefore) existing technologies beget further technologies, can we arrive at a mechanism for the evolution of technology? My answer is yes. Stated in a few words this would work as follows. Early technologies form using existing primitive technologies as components. These new technologies in time become possible components -- building blocks -- for the construction of further new technologies. Some of these in turn go on to become possible building blocks for the creation of yet newer technologies. In this way, slowly over time, many technologies form from an initial few, and more complex ones form using simpler ones as components. The overall collection of technologies bootstraps itself upward from the few to the many and from the simple to the complex. We can say that technology creates itself out of itself.

I will call this mechanism evolution by combination, or more succinctly, combinatorial evolution.

Of course, the argument as I have stated it is not quite complete. Combination cannot be the only mechanism behind technology's evolution. If it were, modern technologies such as radar or magnetic resonance imaging (the MRI of hospital use) would be created out of bow-drills and pottery-firing techniques, or whatever else we deem to have existed at the start of technological time. And we would have a problem designating the start of this technological time. If bowdrills and pottery-firing techniques themselves formed by combination of earlier technologies, where did these ur-technologies come from? We land in an infinite regress. Something else, something more than mere combination, must be going on to create novel technologies.

That something else, I will argue, is the constant capture of new natural phenomena and the harnessing of these for particular purposes. In the cases of radar and MRI, the harnessed phenomena are the reflection of electromagnetic waves and nuclear magnetic resonance, and the purposes are the detection of aircraft and diagnostic imaging of the body. Technology builds out not just from combination of what exists already but from the constant capturing and harnessing of natural phenomena. At the very start of technological time, we directly picked up and used phenomena: the heat of fire, the sharpness of flaked obsidian, the momentum of stone in motion. All that we have achieved since comes from harnessing these and other phenomena, and combining the pieces that result.

In bare-bones form like this the argument is easy to state, but to make it precise many details will need to be worked out. I will have to specify what it really means that novel technologies are "combinations" of existing ones. Technologies are not thrown together randomly as combinations of existing components, so I will have to provide the detailed mechanics of how combination works -- of how, say, the turbojet arises as a combination of existing things. This means, to take things back a further step, we will have to look at how technologies are logically structured, because combination -- however it happens -- must take place in accordance with that structure. We will have to look at the considerable part human beings, in particular their minds, play in this combination process; new technologies are constructed mentally before they are constructed physically, and this mental process will need to be carefully looked into. We will have to pay attention to why technologies come into existence at all: how human needs call for the creation of new technologies. We will have to make clear what it means that technologies beget further technologies -- that novel technologies issue forth from the collective of existing ones. And to take things right back to fundamentals, we will have to define clearly what we mean by "technology."

The Themes of the Book

This book is an argument about what technology is and how it evolves. It is an attempt to construct a theory of technology, "a coherent group of general propositions," we can use to explain technology's behavior. In particular it is an attempt to create a theory of evolution for technology.

My plan is to start from a completely blank state, taking nothing about technology for granted. I will build the argument piece by piece from three fundamental principles. The first will be the one I have been talking about: that technologies, all technologies, are combinations. This simply means that individual technologies are constructed or put together -- combined -- from components or assemblies or subsystems at hand. The second will be that each component of technology is itself in miniature a technology. This sounds odd and I will have to justify it, but for now think of it as meaning that because components carry out specific purposes just as overall technologies do, they too qualify as technologies. And the third fundamental principle will be that all technologies harness and exploit some effect or phenomenon, usually several.

I will say more about these central principles as we go. But notice they immediately give us a view of technologies from the inside. If technologies are combinations they immediately have an interior: they are assembled from parts and groups of parts to meet their purpose. And this interior consists of parts and subsystems that themselves are technologies. We can begin to see that novel technologies originate by piecing together existing ones, and of course by capturing phenomena. We can see technologies developing by changing these interior parts, by swapping in better ones that improve their performance. And we can see different technologies as possessing internal parts inherited in common from previous technologies. Viewed this way technology begins to acquire a "genetics." Nothing equivalent to DNA or its cellular workings of course, or as beautifully ordered as this. But still, a rich interlinked ancestry.

All this sounds organic -- very organic -- and indeed the view we will be led to is as much biological as mechanical. For sure, technologies are not biological organisms, they are mechanistic almost by definition: whether they are sorting algorithms or atomic clocks, they have parts that interact in predictable ways. But once we lay them out as combinations that can be combined into further combinations, we begin to see them not so much as individual pieces of clockwork but as complexes of working processes that interact with other complexes to form new ones. We see a world where the overall collective body of technology forms new elements -- new technologies -- from existing ones. Technology builds itself organically from itself, and this will be one of the themes of this book.

The change in vision I am proposing, from seeing technologies as stand-alone objects each with a fixed purpose to seeing them as objects that can be formed into endless new combinations, is not just abstract. It is mirrored in a broad shift in the character of technology currently taking place. The old industrial-process technologies of the sort that characterized the manufacturing economy -- the open-hearth process for steelmaking, the cracking process for refining crude oil -- were indeed for the most part fixed. They did one thing only and did it in a fixed place: they processed particular raw material inputs into particular industrial outputs and did this largely in separate, stand-alone factories. But now these relatively independent processing technologies are giving way to technologies of a different type. These can be easily combined and they form building blocks that can be used again and again. Global positioning technology provides direct location, but it rarely stands alone. It is used as an element in combination with other elements to navigate aircraft and ships, to help survey territory, to manage agriculture. It is like a highly reactive building block in chemistry -- the hydroxyl ion, say -- doing little on its own, but appearing in a host of different combinations. The same can be said for other elements of the digital revolution: algorithms, switches, routers, repeaters, web services. And we can say the same for the elements that comprise modern genetic engineering or nanotechnology. These can be fitted together in endless combinations that can be configured and reconfigured on the fly for different purposes as conditions demand. These too form building blocks available for continual combination.

Modern technology is not just a collection of more or less independent means of production. Rather it is becoming an open language for the creation of structures and functions in the economy. Slowly, at a pace measured in decades, we are shifting from technologies that produced fixed physical outputs to technologies whose main character is that they can be combined and configured endlessly for fresh purposes.

Technology, once a means of production, is becoming a chemistry.

In attempting to come up with a theory of technology, our first challenge will be to see if we can say something general about it. It is not clear a priori that we can. Hydroelectric power, the process of plastic injection molding, and beekeeping, to choose three technologies at random, seem to have nothing in common. But we will see in the next chapter that technologies do share a common logic in the way they are put together. And this will tell us much about how combination has to work, how technologies come into being, how they subsequently develop, and how they evolve.

But before we get to that we have to settle an even more fundamental question. What exactly is technology, anyway? Copyright © 2009 by W. Brian Arthur



Excerpted from The Nature of Technology: What It Is and How It Evolves by W. Brian Arthur
All rights reserved by the original copyright owners. Excerpts are provided for display purposes only and may not be reproduced, reprinted or distributed without the written permission of the publisher.