I wake up wondering if we're near mountains because of memory or because of something in the air. We're in a beautiful old wooden room of a hotel. The sun is shining on the dark wood through the window shade, but even with the shade drawn I can sense that we're near mountains. There's mountain air in this room. It's cool and moist and almost fragrant. One deep breath makes me ready for the next one and then the next one and with each deep breath I feel a little readier until I jump out of bed and pull up the shade and let all that sunlight in...brilliant, cool, bright, sharp and clear.

An urge grows to go over and push Chris up and down to bounce him awake to see all this, but out of kindness, or respect maybe, he is allowed to sleep a while longer, and so with razor and soap I go to a common washroom at the other end of a long corridor of the same dark wood, floorboards creaking all the way. In the washroom the hot water is steaming and perking in the pipes, too hot at first for shaving, but fine after I mix it with cold water.

Through the window beyond the mirror I see there is a porch out in back, and when done go out and stand on it. It's at a level with the tops of the trees surrounding the hotel which seem to respond to this morning air the same way I do. The branches and leaves move with each light breeze as if it were expected, were what had been waited for all this time.

Chris is soon up and Sylvia comes out of her room saying she and John have already eaten breakfast and he is out walking somewhere, but she will go with Chris and me and walk down with us to breakfast

We are in love with everything this morning and talk about good things all the way down a sunlit morning street to a restaurant. The eggs and hot cakes and coffee are from heaven. Sylvia and Chris talk intimately about his school and friends and personal things, while I listen and gaze through the large restaurant window at the storefront across the road. So different now from that lonely night in South Dakota. Beyond those buildings are mountains and snowfields.

Sylvia says John has talked to someone in town about another route to Bozeman, south through Yellowstone Park.

"South?" I say. "You mean Red Lodge?"

"I guess so."

A memory comes to me of snowfields in June. "That road goes way up above the timberline."

"Is that bad?" Sylvia asks.

"It'll be cold." In the middle of the snowfields in my mind appear the cycles and us riding on them. "But just tremendous."

We meet John again and it's settled. Soon, beyond a railroad underpass, we are on a twisting blacktop through fields toward the mountains up ahead. This

is a road Phædrus used all the time, and flashes of his memory coincide everywhere. The high, dark Absaroka Range looms directly ahead.

We are following a creek to its source. It contains water that was probably snow less than an hour ago. The stream and the road pass through green and stony fields each a little higher than before. Everything is so intense in this sunlight. Dark shadows, bright light. Dark blue sky. The sun is bright and hot when we're in it, but when we pass under trees along the road, it's suddenly cold.

We play tag with a little blue Porsche along the way, passing it with a beep and being passed by it with a beep and doing this several times through fields of dark aspen and bright greens of grass and mountain shrubs. All this is remembered.

He would use this route to get into the high country, then backpack in from the road for three or four or five days, then come back out for more food and head back in again, needing these mountains in an almost physio- logical way. The train of his abstractions became so long and so involved he had to have the surroundings of silence and space here to hold it straight. It was as though hours of constructions would have been shattered by the least distraction of other thought or other duty. It wasn't like other people's thinking, even then, before his insanity. It was at a level at which everything shifts and changes, at which institutional values and verities are gone and there is nothing but one's own spirit to keep one going. His early failure had released him from any felt obligation to think along institutional lines and his thoughts were already independent to a degree few people are familiar with. He felt that institutions such as schools, churches, governments and political organizations of every sort all tended to direct thought for ends other than truth, for the perpetuation of their own functions, and for the control of individuals in the service of these functions. He came to see his early failure as a lucky break, an accidental escape from a trap that had been set for him, and he was very trap-wary about institutional truths for the remainder of his time. He didn't see these things and think this way at first, however, only later on. I'm getting way out of sequence here. This all came much later.

At first the truths Phædrus began to pursue were lateral truths; no longer the frontal truths of science, those toward which the discipline pointed, but the kind of truth you see laterally, out of the corner of your eye. In a laboratory situation, when your whole procedure goes haywire, when everything goes wrong or is indeterminate or is so screwed up by unexpected results you can't make head or tail out of anything, you start looking laterally. That's a word he later used to describe a growth of knowledge that doesn't move forward like an arrow in flight, but expands sideways, like an arrow enlarging in flight, or like the archer, discovering that although he has hit the bull's eye and won the prize, his head is on a pillow and the sun is coming in the window. Lateral knowledge is knowledge that's from a wholly unexpected direction, from a direction that's not even understood as a direction until the knowledge forces itself upon one. Lateral truths point to the falseness of axioms and postulates underlying one's existing system of getting at truth.

To all appearances he was just drifting. In actuality he was just drifting. Drifting is what one does when looking at lateral truth. He couldn't follow any known method of procedure to uncover its cause because it was these methods and procedures that were all screwed up in the first place. So he drifted. That was all he could do.

The drift took him into the Army, which sent him to Korea. From his memory there's a fragment, a picture of a wall, seen from a prow of a ship, shining radiantly, like a gate of heaven, across a misty harbor. He must have valued the fragment greatly and thought about it many times because although it doesn't fit anything else it is intense, so intense I've returned to it myself many times. It seems to symbolize something very important, a turning point.

His letters from Korea are radically different from his earlier writing, indicating this same turning point. They just explode with emotion. He writes page after page about tiny details of things he sees: marketplaces, shops with sliding glass doors, slate roofs, roads, thatched huts, everything. Sometimes full of wild enthusiasm, sometimes depressed, sometimes angry, sometimes even humorous, he is like someone or some creature that has found an exit from a cage he did not even know was around him, and is wildly roaming over the countryside visually devouring everything in sight.

Later he made friends with Korean laborers who spoke some English but wanted to learn more so that they could qualify as translators. He spent time with them after working hours and in return they took him on long weekend hikes through the hills to see their homes and friends and translate for him the way of life and thought of another culture.

He is sitting by a footpath on a beautiful windswept hillside overlooking the Yellow Sea. The rice in the terrace below the footpath is full-grown and brown. His friends look down at the sea with him seeing islands far out from shore. They eat a picnic lunch and talk to one another and to him and the subject is ideographs and their relation to the world. He comments on how amazing it is that everything in the universe can be described by the twenty-six written characters with which they have been working. His friends nod and smile and eat the food they've taken from tins and say no pleasantly. He is confused by the nod yes and the answer no and so repeats the statement. Again comes the nod meaning yes and the answer no. That is the end of the fragment, but like the wall it's one he thinks about many times.

The final strong fragment from that part of the world is of a compartment of a troopship. He is on his way home. The compartment is empty and unused. He is alone on a bunk made of canvas laced to a steel frame, like a trampoline. There are five of these to a tier, tier after tier of them, completely filling the empty troop compartment.

This is the foremost compartment of the ship and

the canvas in the adjoining frames rises and falls, accompanied by elevator feelings in his stomach. He contemplates these things and a deep booming on the steel plates all around him and realizes that except for these signs there is no indication whatsoever that this entire compartment is rising massively high up into the air and then plunging down, over and over again. He wonders if it is that which is making it difficult to concentrate on the book before him, but realizes that no, the book is just hard. It's a text on Oriental philosophy and it's the most difficult book he's ever read. He's glad to be alone and bored in this empty troop compartment, otherwise he'd never get through it.

The book states that there's a theoretic component of man's existence which is primarily Western (and this corresponded to Phædrus' laboratory past) and an esthetic component of man's existence which is seen more strongly in the Orient (and this corresponded to Phædrus' Korean past) and that these never seem to meet. These terms "theoretic" and "esthetic" correspond to what Phædrus later called classic and romantic modes of reality and probably shaped these terms in his mind more than he ever knew. The difference is that the classic reality is primarily theoretic but has its own esthetics too. The romantic reality is primarily esthetic, but has its theory too. The theoretic and esthetic split is between components of a single world. The classic and romantic split is between two separate worlds. The philosophy book, which is called The Meeting of East and West, by F. S. C. Northrop, suggests that greater cognizance be made of the "undifferentiated aesthetic continuum" from which the theoretic arises.

Phædrus didn't understand this, but after arriving in Seattle, and his discharge from the Army, he sat in his hotel room for two whole weeks, eating enormous Washington apples, and thinking, and eating more apples, and thinking some more, and then as a result of all these fragments, and thinking, returned to the University to study philosophy. His lateral drift was ended. He was actively in pursuit of something now.

A sudden cross-gust of cold air comes heavy with the smell of pines, and soon another and another, and as we approach Red Lodge I'm shivering.

At Red Lodge the road's almost joined to the base of the mountain. The dark ominous mass beyond dominates even the roofs of the buildings on either side of the main street. We park the cycles and unpack them to remove warm clothing. We walk past ski shops into a restaurant where we see on the walls huge photographs of the route we will take up. And up and up, over one of the highest paved roads in the world. I feel some anxiety about this, which I realize is irrational and try to get rid of by talking about the road to the others. There's no way to fall off. No danger to the motorcycle. Just a memory of places where you could throw a stone and it would drop thousands of feet before coming to rest and somehow associating that stone with the cycle and rider.

When coffee is finished we put on the heavy clothing, repack and have soon traveled to the first of many switchback turns across the face of the mountain.

The asphalt of the road is much wider and safer than it occurred in memory. On a cycle you have all sorts of extra room. John and Sylvia take the hairpin turns up ahead and then come back above us, facing us, and have smiles. Soon we take the turn and see their backs again. Then another turn for them and we meet them again, laughing. It's so hard when contemplated in advance, and so easy when you do it.

I talked about Phædrus' lateral drift, which ended with entry into the discipline of philosophy. He saw philosophy as the highest echelon of the entire hierarchy of knowledge. Among philosophers this is so widely believed it's almost a platitude, but for him it's a revelation. He discovered that the science he'd once thought of as the whole world of knowledge is only a branch of philosophy, which is far broader and far more general. The questions he had asked about infinite hypotheses hadn't been of interest to science because they weren't scientific questions. Science cannot study scientific method without getting into a bootstrap problem that destroys the validity of its answers. The questions he'd asked were at a higher level than science goes. And so Phædrus found in philosophy a natural continuation of the question that brought him to science in the first place, What does it all mean? What's the purpose of all this?

At a turnout on the road we stop, take some record photographs to show we have been here and then walk to a little path that takes us out to the edge of a cliff. A motorcycle on the road almost straight down beneath us could hardly be seen from up here. We bundle up more tightly against the cold and continue upward.

The broad-leafed trees are all gone. Only small pines are left. Many of these have twisted and stunted shapes.

Soon stunted pines disappear entirely and we're in alpine meadows. There's not a tree anywhere, only grass everywhere filled with little pink and blue and white dots of intense color. Wildflowers, everywhere! These and grasses and mosses and lichens are all that can live here, now. We've reached the high country, above the timberline.

I look over my shoulder for one last view of the gorge. Like looking down at the bottom of the ocean. People spend their entire lives at those lower altitudes without any awareness that this high country exists.

The road turns inward, away from the gorge and into snowfields.

The engine backfires fiercely from lack of oxygen and threatens to stop but never does. Soon we are between banks of old snow, the way snow looks in early spring after a thaw. Little streams of water run everywhere into mossy mud, and then below this into week-old grass and then small wildflowers, the tiny pink and blue and yellow and white ones which seem to pop out, sun-brilliant, from black shadows. Everywhere it's like this! Little pins of colored light shoot forth to me from a background of somber dark green and black. Dark sky now and cold. Except where the sun hits. On the sun side my arm and leg and jacket are hot, but the dark side, in deep shadows now, is very cold.

The snowfields become heavy and show steep banks where snowplows have been. The banks become four feet high, then six feet, then twelve feet high. We move through twin walls, almost a tunnel of snow. Then the tunnel opens onto dark sky again and when we emerge we see we're at the summit.

Beyond is another country. Mountain lakes and pines and snowfields are below. Above and beyond them as far as we can see are farther mountain ranges covered with snow. The high country.

We stop and park at a turnoff where a number of tourists take pictures and look around at the view and at one other. At the back of his cycle John removes his camera from the saddlebag. From my own machine I remove the tool kit and spread it out on the seat, then take the screwdriver, start the engine and with the screwdriver adjust the carburetors until the idling sound changes from a really bad loping to just slightly bad. I'm surprised at how all the way up it backfired and sputtered and kicked and gave every indication it was going to quit but never did. I didn't adjust them, out of curiosity to see what eleven thousand feet of altitude would do. Now I'm leaving them rich and sounding just bad because we'll be going down some now toward Yellowstone Park and if they aren't slightly rich now they'll get too lean later on, which is dangerous because it overheats the engine.

The backfiring is still fairly heavy on the way down from the summit with the engine dragging in second gear, but then the noise diminishes as we reach lower altitudes. The forests return. We move among rocks and lakes and trees now, taking beautiful turns and curves of the road.

I want to talk about another kind of high country now in the world of thought, which in some ways, for me at least, seems to parallel or produce feelings similar to this, and call it the high country of the mind.

If all of human knowledge, everything that's known, is believed to be an enormous hierarchic structure, then the high country of the mind is found at the uppermost reaches of this structure in the most general, the most abstract considerations of all.

Few people travel here. There's no real profit to be made from wandering through it, yet like this high country of the material world all around us, it has its own austere beauty that to some people makes the hardships of traveling through it seem worthwhile.

In the high country of the mind one has to become adjusted to the thinner air of uncertainty, and to the enormous magnitude of questions asked, and to the answers proposed to these questions. The sweep goes on and on and on so obviously much further than the mind can grasp one hesitates even to go near for fear of getting lost in them and never finding one's way out.

What is the truth and how do you know it when you have it? -- How do we really know anything? Is there an "I," a "soul," which knows, or is this soul merely cells coordinating senses? -- Is reality basically changing, or is it fixed and permanent? -- When it's said that something means something, what's meant by that?

Many trails through these high ranges have been made and forgotten since the beginning of time, and although the answers brought back from these trails have claimed permanence and universality for themselves, civilizations have varied in the trails they have chosen and we have many different answers to the same question, all of which can be thought of as true within their own context. Even within a single civilization old trails are constantly closed and new ones opened up.

It's sometimes argued that there's no real progress; that a civilization that kills multitudes in mass warfare, that pollutes the land and oceans with ever larger quantities of debris, that destroys the dignity of individuals by subjecting them to a forced mechanized existence can hardly be called an advance over the simpler hunting and gathering and agricultural existence of prehistoric times. But this argument, though romantically appealing, doesn't hold up. The primitive tribes permitted far less individual freedom than does modern society. Ancient wars were committed with far less moral justification than modern ones. A technology that produces debris can find, and is finding, ways of disposing of it without ecological upset. And the schoolbook pictures of primitive man sometimes omit some of the detractions of his primitive life...the pain, the disease, famine, the hard labor needed just to stay alive. From that agony of bare existence to modern life can be soberly described only as upward progress, and the sole agent for this progress is quite clearly reason itself.

One can see how both the informal and formal processes of hypothesis, experiment, conclusion, century after century, repeated with new material, have built up the hierarchies of thought which have eliminated most of the enemies of primitive man. To some extent the romantic condemnation of rationality stems from the very effectiveness of rationality in uplifting men from primitive conditions. It's such a powerful, all-dominating agent of civilized man it's all but shut out everything else and now dominates man himself. That's the source of the complaint.

Phædrus wandered through this high country, aimlessly at first, following every path, every trail where someone had been before, seeing occasionally with small hindsights that he was apparently making some progress, but seeing nothing ahead of him that told him which way to go.

Through the mountainous questions of reality and knowledge had passed great figures of civilization, some of whom, like Socrates and Aristotle and Newton and Einstein, were known to almost everyone, but most of whom were far more obscure. Names he had never heard of before. And he became fascinated with their thought and their whole way of thinking. He followed their trails carefully until they seemed to grow cold, then dropped them. His work was just barely passing by academic standards at this time, but this wasn't because he wasn't working or thinking. He was thinking too hard, and the harder you think in this high country of the mind the slower you go. Phædrus read in a scientific way rather than a literary way, testing each sentence as he went along, noting doubts and questions to be resolved later, and I'm fortunate in having a whole trunkful of volumes of these notations.

What is most astonishing about them is that almost everything he said years later is contained in them. It's frustrating to see how completely unaware he is at the time of the significance of what he is saying. It's like seeing someone handling, one by one, all the pieces of a jigsaw puzzle whose solution you know, and you want to tell him, "Look, this fits here, and this fits here," but you can't tell him. And so he wanders blindly along one trail after another gathering one piece after another and wondering what to do with them, and you grit your teeth when he goes off on a false trail and are relieved when he comes back again, even though he is discouraged himself. "Don't worry," you want to tell him. "Keep going!"

But he's such an abominable scholar it must be through the kindness of his instructors that he passes at all. He prejudges every philosopher he studies. He always intrudes and imposes his own views upon the material he is studying. He is never fair. He's always partial. He wants each philosopher to go a certain way and becomes infuriated when he does not.

A fragment of memory is preserved of him sitting in a room at three and four in the morning with Immanuel Kant's famous Critique of Pure Reason, studying it as a chess player studies the openings of the tournament masters, trying to test the line of development against his own judgment and skill, looking for contradictions and incongruities.

Phædrus is a bizarre person when contrasted to the twentieth-century Midwestern Americans who surround him, but when he is seen studying Kant he is less strange. For this eighteenth-century German philosopher he feels a respect that rises not out of agreement but out of appreciation for Kant's formidable logical fortification of his position. Kant is always superbly methodical, persistent, regular and meticulous as he scales that great snowy mountain of thought concerning what is in the mind and what is outside the mind. It is, for modern climbers, one of the highest peaks of all, and I want now to magnify this picture of Kant and show a little about how he thought and how Phædrus thought about him in order to give a clearer picture of what the high country of the mind is like and also to prepare the way for an understanding of Phædrus' thoughts.

Phædrus' resolution of the entire problem of classic and romantic understanding occurred at first in this high country of the mind, and unless one understands the relation of this country to the rest of existence, the meaning and the importance of lower levels of what he said here will be underestimated or misunderstood.

To follow Kant one must also understand something about the Scottish philosopher David Hume. Hume had previously submitted that if one follows the strictest rules of logical induction and deduction from experience to determine the true nature of the world, one must arrive at certain conclusions. His reasoning followed lines that would result from answers to this question: Suppose a child is born devoid of all senses; he has no sight, no hearing, no touch, no smell, no taste...nothing. There's no way whatsoever for him to receive any sensations from the outside world. And suppose this child is fed intravenously and otherwise attended to and kept alive for eighteen years in this state of existence. The question is then asked: Does this eighteen-year-old person have a thought in his head? If so, where does it come from? How does he get it?

Hume would have answered that the eighteen-year-old had no thoughts whatsoever, and in giving this answer would have defined himself as an empiricist, one who believes all knowledge is derived exclusively from the senses. The scientific method of experimentation is carefully controlled empiricism. Common sense today is empiricism, since an overwhelming majority would agree with Hume, even though in other cultures and other times a majority might have differed.

The first problem of empiricism, if empiricism is believed, concerns the nature of "substance." If all our knowledge comes from sensory data, what exactly is this substance which is supposed to give off the sensory data itself? If you try to imagine what this substance is, apart from what is sensed, you'll find yourself thinking about nothing whatsoever.

Since all knowledge comes from sensory impressions and since there's no sensory impression of substance itself, it follows logically that there is no knowledge of substance. It's just something we imagine. It's entirely within our own minds. The idea that there's something out there giving off the properties we perceive is just another of those common-sense notions similar to the common-sense notion children have that the earth is flat and parallel lines never meet.

Secondly, if one starts with the premise that all our knowledge comes to us through our senses, one must ask, From what sense data is our knowledge of causation received? In other words, what is the scientific empirical basis of causation itself?

Hume's answer is "None." There's no evidence for causation in our sensations. Like substance, it's just something we imagine when one thing repeatedly follows another. It has no real existence in the world we observe. If one accepts the premise that all knowledge comes to us through our senses, Hume says, then one must logically conclude that both "Nature" and "Nature's laws" are creations of our own imagination.

This idea that the entire world is within one's own mind could be dismissed as absurd if Hume had just thrown it out for speculation. But he was making it an airtight case.

To throw out Hume's conclusions was necessary, but unfortunately he had arrived at them in such a way that it was seemingly impossible to throw them out without abandoning empirical reason itself and retiring into some medieval predecessor of empirical reason. This Kant would not do. Thus it was Hume, Kant said, who "aroused me from my dogmatic slumbers" and caused him to write what is now regarded as one of the greatest philosophical treatises ever written, the Critique of Pure Reason, often the subject of an entire University course.

Kant is trying to save scientific empiricism from the consequences of its own self-devouring logic. He starts out at first along the path that Hume has set before him. "That all our knowledge begins with experience there can be no doubt," he says, but he soon departs from the path by denying that all components of knowledge come from the senses at the moment the sense data are received. "But though all knowledge begins with experience it doesn't follow that it arises out of experience."

This seems, at first, as though he is picking nits, but he isn't. As a result of this difference, Kant skirts right around the abyss of solipsism that Hume's path leads to and proceeds on an entirely new and different path of his own.

Kant says there are aspects of reality which are not supplied immediately by the senses. These he calls a priori. An example of a priori knowledge is "time." You don't see time. Neither do you hear it, smell it, taste it or touch it. It isn't present in the sense data as they are received. Time is what Kant calls an "intuition," which the mind must supply as it receives the sense data.

The same is true of space. Unless we apply the concepts of space and time to the impressions we receive, the world is unintelligible, just a kaleidoscopic jumble of colors and patterns and noises and smells and pain and tastes without meaning. We sense objects in a certain way because of our application of a priori intuitions such as space and time, but we do not create these objects out of our imagination, as pure philosophical idealists would maintain. The forms of space and time are applied to data as they are received from the object producing them. The a priori concepts have their origins in human nature so that they're neither caused by the sensed object nor bring it into being, but provide a kind of screening function for what sense data we will accept. When our eyes blink, for example, our sense data tell us that the world has disappeared. But this is screened out and never gets to our consciousness because we have in our minds an a priori concept that the world has continuity. What we think of as reality is a continuous synthesis of elements from a fixed hierarchy of a priori concepts and the ever changing data of the senses. Now stop and apply some of the concepts Kant has put forth to this strange machine, this creation that's been bearing us along through time and space. See our relation to it now, as Kant reveals it to us.

Hume has been saying, in effect, that everything I know about this motorcycle comes to me through my senses. It has to be. There's no other way. If I say it's made of metal and other substances, he asks, What's metal? If I answer that metal's hard and shiny and cold to the touch and deforms without breaking under blows from a harder material, Hume says those are all sights and sounds and touch. There's no substance. Tell me what metal is apart from these sensations. Then, of course, I'm stuck.

But if there's no substance, what can we say about the sense data we receive? If I hold my head to the left and look down at the handle grips and front wheel and map carrier and gas tank I get one pattern of sense data. If I move my head to the right I get another slightly different pattern of sense data. The two views are different. The angles of the planes and curves of the metal are different. The sunlight strikes them differently. If there's no logical basis for substance then there's no logical basis for concluding that what's produced these two views is the same motorcycle.

Now we've a real intellectual impasse. Our reason, which is supposed to make things more intelligible, seems to be making them less intelligible, and when reason thus defeats its own purpose something has to be changed in the structure of our reason itself.

Kant comes to our rescue. He says that the fact that there's no way of immediately sensing a "motorcycle," as distinguished from the colors and shapes a motorcycle produces, is no proof at all that there's no motorcycle there. We have in our minds an a priori motorcycle which has continuity in time and space and is capable of changing appearance as one moves one's head and is therefore not contradicted by the sense data one is receiving.

Hume's motorcycle, the one that makes no sense at all, will occur if our previous hypothetical bed patient, the one who has no senses at all, is suddenly, for one second only, exposed to the sense data of a motorcycle, then deprived of his senses again. Now, I think, in his mind he would have a Hume motorcycle, which provides him with no evidence whatsoever for such concepts as causation.

But, as Kant says, we are not that person. We have in our minds a very real a priori motorcycle whose existence we have no reason to doubt, whose reality can be confirmed anytime.

This a priori motorcycle has been built up in our minds over many years from enormous amounts of sense data and it is constantly changing as new sense data come in. Some of the changes in this specific a priori motorcycle I'm riding are very quick and transitory, such as its relationship to the road. This I'm monitoring and correcting all the time as we take these curves and bends in the road. As soon as the information's of no more value I forget it because there's more coming in that must be monitored. Other changes in this a priori are slower: Disappearance of gasoline from the tank. Disappearance of rubber from the tires. Loosening of bolts and nuts. Change of gap between brake shoes and drums. Other aspects of the motorcycle change so slowly they seem permanent...the paint job, the wheel bearings, the control cables...yet these are constantly changing too. Finally, if one thinks in terms of really large amounts of time even the frame is changing slightly from the road shocks and thermal changes and forces of internal fatigue common to all metals.

It's quite a machine, this a priori motorcycle. If you stop to think about it long enough you'll see that it's the main thing. The sense data confirm it but the sense data aren't it. The motorcycle that I believe in an a priori way to be outside of myself is like the money I believe I have in the bank. If I were to go down to the bank and ask to see my money they would look at me a little peculiarly. They don't have "my money" in any little drawer that they can pull open to show me. "My money" is nothing but some east-west and north-south magnetic domains in some iron oxide resting on a roll of tape in a computer storage bin. But I'm satisfied with this because I've faith that if I need the things that money enables, the bank will provide the means, through their checking system, of getting it. Similarly, even though my sense data have never brought up anything that could be called "substance" I'm satisfied that there's a capability within the sense data of achieving the things that substance is supposed to do, and that the sense data will continue to match the a priori motorcycle of my mind. I say for the sake of convenience that I've money in the bank and say for the sake of convenience that substances compose the cycle I'm riding on. The bulk of Kant's Critique of Pure Reason is concerned with how this a priori knowledge is acquired and how it is employed.

Kant called his thesis that our a priori thoughts are independent of sense data and screen what we see a "Copernican revolution." By this he referred to Copernicus' statement that the earth moves around the sun. Nothing changed as a result of this revolution, and yet everything changed. Or, to put it in Kantian terms, the objective world producing our sense data did not change, but our a priori concept of it was turned inside out. The effect was overwhelming. It was the acceptance of the Copernican revolution that distinguishes modern man from his medieval predecessors.

What Copernicus did was take the existing a priori concept of the world, the notion that it was flat and fixed in space, and pose an alternative a priori concept of the world, that it's spherical and moves around the sun; and showed that both of the a priori concepts fitted the existing sensory data.

Kant felt he had done the same thing in metaphysics. If you presume that the a priori concepts in our heads are independent of what we see and actually screen what we see, this means that you are taking the old Aristotelian concept of scientific man as a passive observer, a "blank tablet," and truly turning this concept inside out. Kant and his millions of followers have maintained that as a result of this inversion you get a much more satisfying understanding of how we know things.

I've gone into this example in some detail, partly to show some of the high country in close perspective, but more to prepare for what Phædrus did later. He too performed a Copernican inversion and as a result of this inversion produced a resolution of the separate worlds of classical and romantic understanding. And it seems to me that as a result it is possible to again get a much more satisfying understanding of what the world is all about.