The main idea is to be interesting

H.L. Mencken in Newspaper Morals.

Aspiring, toward the end of my nonage, to the black robes of a dramatic critic, I took counsel with an ancient whose service went back to the days of Our American Cousin, asking him what qualities were chiefly demanded by the craft.

'The main idea,' he told me frankly, 'is to be interesting, to write a good story. All else is dross. Of course, I am not against accuracy, fairness, information, learning. If you want to read Lessing and Freytag, Hazlitt and Brunetiere, go read them: they will do you no harm. It is also useful to know something about Shakespeare. But unless you can make people read your criticisms, you may as well shut up your shop. And the only way to make them read you is to give them something exciting.'

Footprints on the sands of time

A Psalm of Life
by Henry Wadsworth Longfellow

What the heart of the young man said to the psalmist

Tell me not, in mournful numbers,
Life is but an empty dream! -
For the soul is dead that slumbers,
And things are not what they seem.

Life is real! Life is earnest!
And the grave is not its goal;
Dust thou art, to dust returnest,
Was not spoken of the soul.

Not enjoyment, and not sorrow,
Is our destined end or way;
But to act, that each to-morrow
Find us farther than to-day.

Art is long, and Time is fleeting,
And our hearts, though stout and brave,
Still, like muffled drums, are beating
Funeral marches to the grave.

In the world's broad field of battle,
In the bivouac of Life,
Be not like dumb, driven cattle!
Be a hero in the strife!

Trust no Future, howe'er pleasant!
Let the dead Past bury its dead!
Act,- act in the living Present!
Heart within, and God o'erhead!

Lives of great men all remind us
We can make our lives sublime,
And, departing, leave behind us
Footprints on the sands of time;

Footprints, that perhaps another,
Sailing o'er life's solemn main,
A forlorn and shipwrecked brother,
Seeing, shall take heart again.

Let us, then, be up and doing,
With a heart for any fate;
Still achieving, still pursuing,
Learn to labor and to wait.

Importance versus Epistemological Uncertainty

In thinking about reading, behaviors, cultures, and problem solving, it seems to me as if there is probably a hierarchy of questions that can be asked of any situation, problem, or issue. There are approaches to problem solving that require the asking of questions and sometimes the standard questions of who, what, where, when, why and how are referred to as the six servants of inquiry. In fact Rudyard Kipling had a short poem (in The Elephant's Child)

My Six Servants
by Rudyard Kipling

I keep six honest serving-men
They taught me all I knew;
Their names are What and Why and When
And How and Where and Who.

Reporters historically have been counselled to focus on Who and What to lead their stories, followed by Why, When, How, and Where.

In investigating an issue or problem, though, it seems to me as if there is a different hierarchy. There are some things that are relatively easy to know, the What, Where, and When. Not that these are necessarily easy to know, but easier to know. They can be determined with some degree of objectivity. What Happened?: A murder occurred. Where Did it Happen?: In the parlor. When Did it Happen?: Last night.

Then you get to the next more complicated aspect. To whom did this happen. Sometimes it is quite clear, in other cases, it is less obvious. Next you have the question of Who did it. It seems as if you are moving along an axis where the degree of certainty becomes less and less. You can usually figure out who did it but there is always at least some modicum of doubt.

Then you take a big leap of epistemological uncertainty: How did it happen? What were the sequence of steps and dependent actions that led to this outcome at this place and at this time to this person(s). That is a much more tangled tale and subject to greater doubt. Some pieces are clear - Action B had to follow Action A. Other times, it is a matter of probability: This probably followed that.

Finally you come to the question with the greatest uncertainty of all - Why did this happen. As it goes to motive, state-of-mind, and estimation, this necessarily is the least certain answer of all. We can guess, we can speculate. We can identify multiple probable causes but our ability to be certain is low.

While we are venturing along the axis of epistemological uncertainty, we are also climbing an axis of importance to forecasting. Knowing what happened, where it happened and when it happened may help a little bit in estimating the probability of it happening again, but probably not a lot of help. Knowing the individuals and personal dynamics helps more. Knowing how something happened helps a lot in forecasting the future probability. Knowing why it happened helps the most.

This progression might look something like this.

In solving a problem, answering a question, or determining some prospective course of action, we are always dependent on knowing the background and the context. However, knowing the simple facts (What, Where, When, Who) is never enough. We need to know the How and the Why but they are the pieces of knowledge in which we are the least confident. The movement along that line of questions takes you from the objective, the factual, the logical, into the realm of the subjective, the probable, the motivational.

Enthusiasts with something to sell

From Jacques Barzun's Begin Here: The Forgotten Conditions of Teaching and Learning

. . .another illusion bred by university research, the idea of the obsolete, the apparent elimination of the past by the future, the belief propagated by science and industry that later is better, even when later has not yet come about and is only a prophecy by enthusiasts with something to sell.

Vilified by base and illiterate scribblers

From Robert Burton's The Anatomy of Melancholy.

"With us in France," saith Scaliger, "every man hath liberty to write, but few ability." "Heretofore learning was graced by judicious scholars, but now noble sciences are vilified by base and illiterate scribblers," that either write for vainglory, need, to get money, or as Parasites to flatter and collogue with some great men, they put cut burras, quisquiliasque ineptiasque.

Amongst so many thousand authors you shall scarce find one, by reading of whom you shall be any whit better, but rather much worse, quibus inficitur potius, quam perficitur,
by which he is rather infected than any way perfected.

------ Qui talia legit,
Quid didicit tandem, quid scit nisi somnia, nugas?

So that oftentimes it falls out (which Callimachus taxed of old) a great book is a great mischief. Cardan finds fault with Frenchmen and Germans, for their scribbling to no purpose, non inquit ab edendo deterreo, modo novum aliquid inveniant, he doth not bar them to write, so that it be some new invention of their own; but we weave the same web still, twist the same rope again and again; or if it be a new invention, 'tis but some bauble or toy which idle fellows write, for as idle fellows to read, and who so cannot invent? "He must have a barren wit, that in this scribbling age can forge nothing. Princes show their armies, rich men vaunt their buildings, soldiers their manhood, and scholars vent their toys;" they must read, they must hear whether they will or no.

Et quodcunque semel chartis illeverit, omnes
Gestiet a furno redeuntes scire lacuque,
Et pueros et anus . .

What once is said and writ, all men must know,
Old wives and children as they come and go.

"What a company of poets hath this year brought out," as Pliny complains to Sossius Sinesius. "This April every day some or other have recited." What a catalogue of new books all this year, all this age (I say), have our Frankfort Marts, our domestic Marts brought out? Twice a year, Proferunt se nova ingenia et ostentant, we stretch our wits out, and set
them to sale, magno conatu nihil agimus. So that which Gesner much desires, if a speedy reformation be not had, by some prince's edicts and grave supervisors, to restrain this liberty, it will run on in infinitum. Quis tam avidus librorum helluo, who can read them? As already, we shall have a vast chaos and confusion of books, we are oppressed with them, our eyes ache with reading, our fingers with turning.

The multitude of books

Adrien Baillet in Jugemens des savants sur les principaux ouvrages des auteurs in 1725.

We have reason to fear that the multitude of books that are increasing every day in a prodigious manner will put the centuries to come into as difficult a state as that in which barbarity had put the earlier ones after the fall of the Roman Empire. Unless we try to prevent this danger by separating those books which we must throw out or leave in oblivion from those which one should save and within the latter between what is useful and what is not.

Be quite candid with ourselves and with the facts

From William James, The Varieties of Religious Experience.

Let us play fair in this whole matter, and be quite candid with ourselves and with the facts. When we think certain states of mind superior to others, is it ever because of what we know concerning their organic antecedents? No! it is always for two entirely different reasons. It is either because we take an immediate delight in them; or else it is because we believe them to bring us good consequential fruits for life.

Canonical Milestones

From The Limits of Complexity by Theodore Modis, an attempt to define and measure complexity. Modis attempts to identify the most significant milestones in history: "The 28 'canonical' milestones, . . . generally represent a cluster of many milestones events." See the article for his methodology which is necessarily open to criticism, but it is an interesting attempt. Below are the 28 inflection points of history which he identifies from a larger complilation from a variety of sources.

1) The Big Bang and associated processes: 15.5 billion years ago

2) Origin of Milky Way, first stars: 10 billion years ago

3) Origin of life on Earth, formation of the solar system and the Earth, oldest rocks: 4 billion years ago

4) First eukaryotes, invention of sex (by microorganisms), atmospheric oxygen, oldest photosynthetic plants, plate tectionics established: 2 billion years ago

5) First multicellular life (sponges, seaweeds, protozoans): 1 billion years ago

6) Cambrian explosion, invertebrates, vertebrates, plants colonize land, first trees, reptiles, insects, amphibians: 430 million years ago

7) First mammals, first birds, first dinosaurs, first use of tools: 210 million years ago

8) First flowering plants, oldest angiosperm fossil: 139 million years ago

9) Asteroid collision, first primates, mass extinction (including dinosaurs): 54.6 million years ago

10) First hominids, first humanoids: 28.5 million years ago

11) First organutan, origin of proconsul: 16.5 million years ago

12) Chimpanzees and humans diverge, earliest hominid bipedalism: 5.1 million years ago

13) First stone tools, first humans, Ice Age, Homo erectus, origin of spoken language: 2.2 million years ago

14) Emergence of Homo sapiens: 550,000 years ago

15) Domestication of fire, Homo heidelbergensis: 325,000 years ago

16) Differentiation of human DNA types: 200,000 years ago

17) Emergence of "modern humans," earliest burial of the dead: 105,000 years ago

18) Rock art, protowriting: 35,800 years ago

19) Invention of agriculture: 19,200 years ago

20) Techniques for starting fire, first cities: 11,000 years ago

21) Development of the wheel, writing, archaic empires: 4,907 years ago

22) Democracy, city-states, the Greeks, Buddha: 2,437 years ago

23) Zero and decimals invented, Rome falls, Moslem conquest: 1,440 years ago

24) Renaissance (printing press), discovery of New World, the scientific method: 539 years ago

25) Industrial revolution (steam engine), political revolutions (France, USA): 250 years ago

26) Modern physics, radio, electricity, automobile, airplane: 100 years ago

27) DNA structure described, transistor invetned, nuclear energy, World War II, Cold War, Sputnik: 50 years ago

28) Internet, human genome sequenced: 5 years ago

An order that always refers to limited aspects of reality

Arthur Koestler in The Act of Creation, p. 253

Einstein's space is no closer to reality than Van Gogh's sky. The glory of science is not in a truth more absolute than the truth of Bach or Tolstoy, but in the act of creation itself. The scientist's discoveries impose his own order on chaos, as the composer or painter imposes his; an order that always refers to limited aspects of reality, and is based on the observer's frame of reference, which differs from period to period as a Rembrant nude differs from a nude by Manet.

Pleasure has no fellowship with virtue

Cicero, De Sectute -

The most noble and excellent gift of heaven to man is reason; and of all the enemies that reason has to engage with, pleasure is the chief. . . . Pleasure has no fellowship with virtue.

Always a child

Cicero:

Not to know what happened before one was born is always to be a child.

They proceed from diverse intellectual preoccupations

From William James, The Varieties of Religious Experience.

In recent books on logic, distinction is made between two orders of inquiry concerning anything. First, what is the nature of it? how did it come about? what is its constitution, origin, and history? And second, What is its importance, meaning, or significance, now that it is once here? The answer to the one question is given in an existential judgment or proposition. The answer to the other is a proposition of value, what the Germans call a Werthurtheil, or what we may, if we like, denominate a spiritual judgment. Neither judgment can be deduced immediately from the other. They proceed from diverse intellectual preoccupations, and the mind combines them only by making them first separately, and then adding them together.

Homer nods

Bertrand Russell in The Impact of Science on Society, page 17

Aristotle maintained that women have fewer teeth than men; although he was twice married, it never occurred to him to verify this statement by examining his wives' mouths.

There are only human beings

From The Scientist in the Crib by Alison Gopnik, Andrew M. Meltzoff, and Patricia K. Kuhl. Page 13

There is still supposed to be a deep split between scientific, cultivated, rational ways of knowing the world and intuitive, natural, emotional ways of knowing. And children (and "primitive" people and women) are still assumed to be the exemplars of intuition rather than science, and passion rather than reason. The debate is still about which side you think you ought to root for.

The new developmental research shows that this historical consensus about children was just plain wrong. Children are not blank tablets or unbridled appetites or even intuitive seers. Babies and young children think, observe, and reason. They consider evidence, draw conclusions, do experiments, solve problems, and search for the truth. Of course, they don't do this in the self-conscious way that scientists do. And the problems they try to solve are everyday problems about what people and objects and words are like, rather than arcane problems about stars and atoms. But even the youngest babies know a great deal about the world and actively work to find out more.

That undermines the entire picture of the great chain of knowing. Women and people from other cultures have, after all, at least escaped the negative implications of being "childlike." (Nowadays it's okay to think women and people from other cultures are intuitive and natural only if you take the positive, Romantic view). But if even children themselves aren't "childlike," the whole picture collapses. There are no savages, noble or otherwise, and there are no "children of nature," not even among children. There are only human beings, children and grown-ups, women and men, hunter-gatherers and scientists, trying to figure out what's going on.

Getting to know the world

Bertrand Russell in The Impact of Science on Society, page 91

Science used to be valued as a means of getting to know the world; now, owing to the triumph of technique, it is conceived as showing how to change the world.

And then I call to mind eternity

The Infinite
by Giacomo Leopardi

Dear to me always was this lonely hill
And this hedge that excludes so large a part
Of the ultimate horizon from my view,
But as I sit and gaze, my thought conceives
Interminable vastnesses of space
Beyond it, and unearthly silences,
And profoundest calm; whereat my heart almost
Becomes dismayed. And as I hear the wind
Blustering through these branches, I find myself
Comparing with this sound that infinite silence;
And then I call to mind eternity,
And the ages that are dead, and this that now
Is living, and the noise of it. And so
In this immensity my thought sinks drowned:
And sweet it seems to shipwreck in this sea.

Evidence

Christopher Hitchens:

What can be asserted without evidence can be dismissed without evidence.

Responsibility must be both definite and limited

Via Saving Hayek from the People Who Think They're Saving Hayek by Jason Kuznicki

A free society will not function or maintain itself unless its members regard it as right that each individual occupy the position that results from his action and accept it as due to his own action. Though it can offer to the individual only chances and though the outcome of his efforts will depend on innumerable accidents, it forcefully directs his attention to those circumstances that he can control as if they were the only ones that mattered (The Constitution of Liberty, Chicago: University of Chicago Press, 1978, p. 78).

The sense of responsibility has been weakened in modern times as much by overextending the range of an individual's responsibilities as by exculpating him from the actual consequences of his actions . . . To be effective, responsibility must be both definite and limited, adapted both emotionally and intellectually to human capacities. It is quite as destructive of any sense of responsibility to be taught that one is responsible for everything as to be taught that one cannot be held responsible for anything . . .

Responsibility, to be effective, must be individual responsibility. In a free society there cannot be any collective responsibility of the members of a group as such, unless they have, by concerted action, all made themselves individually and severally responsible . . . If the same concerns are made the responsibility of many without at the same time imposing a duty of joint and agreed action, the result is usually that nobody really accepts responsibility. As everybody's property in effect is nobody's property, so everybody's responsibility is nobody's responsibility (ibid., p 83).

Sic transit Gloria mundi

From Charles Murray's Human Accomplishment. A very intriguing and rigorous discussion of what constitutes accomplishment, how do we measure it, and how do we explain it.

At the end of 1899, the editor of London's Daily Telegraph, with the assistance of learned consultants, selected the "100 Best Novels in the World" from all the novels in any language. In all, 61 authors were represented in the list of 100 best novels. Only 27 of them - fewer than half - qualified as significant figures in Human Accomplishment's inventory of Western literature. Seventeen of the 61 - 28 percent -were not mentioned even once by any of the 20 sources used to compile that inventory; not even by the most encyclopedic ones. And yet each of those 17 who are now ignored had written one of the supposedly 100 best novels of all times as judged in 1899. Sic transit Gloria mundi.

It is this sort of contemporaneous over-confidence that always makes me leery of the hoopla over the most recently discovered author or new gem of a book. Time tests them all and finds most wanting regardless of what experts and critics might opine.

The chief business of the American people is business

From a speech, The Press Under a Free Government, by Calvin Coolidge, January 17, 1925.

There does not seem to be cause for alarm in the dual relationship of the press to the public, whereby it is on one side a purveyor of information and opinion and on the other side a purely business enterprise. Rather, it is probable that a press which maintains an intimate touch with the business currents of the nation, is likely to be more reliable than it would be if it were a stranger to these influences. After all, the chief business of the American people is business. They are profoundly concerned with producing, buying, selling, investing and prospering in the world. I am strongly of opinion that the great majority of people will always find these are moving impulses of our life. The opposite view was oracularly and poetically set forth in those lines of Goldsmith which everybody repeats, but few really believe:

Ill fares the land, to hastening ills a prey,
Where wealth accumulates, and men decay.

Excellent poetry, but not a good working philosophy. Goldsmith would have been right, if, in fact, the accumulation of wealth meant the decay of men. It is rare indeed that the men who are accumulating wealth decay. It is only when they cease production, when accumulation stops, that an irreparable decay begins. Wealth is the product of industry, ambition, character and untiring effort. In all experience, the accumulation of wealth means the multiplication of schools, the increase of knowledge, the dissemination of intelligence, the encouragement of science, the broadening of outlook, the expansion of liberties, the widening of culture. Of course, the accumulation of wealth can not be justified as the chief end of existence. But we are compelled to recognize it as a means to well nigh every desirable achievement. So long as wealth is made the means and not the end, we need not greatly fear it. And there never was a time when wealth was so generally regarded as a means, or so little regarded as an end, as today. Just a little time ago we read in your newspapers that two leaders of American business, whose efforts at accumulation had been most astonishingly successful, had given fifty or sixty million dollars as endowments to educational works. That was real news. It was characteristic of our American experience with men of large resources. They use their power to serve, not themselves and their own families, but the public. I feel sure that the coming generations, which will benefit by those endowments, will not be easily convinced that they have suffered greatly because of these particular accumulations of wealth.

Time to stop repeating the wise sayings and begin to believe them

From Jacques Barzun's Begin Here: The Forgotten Conditions of Teaching and Learning

But the reward of reading with a humanistic eye is not in doubt: it is pleasure, renewable at will. That pleasure is the ultimate use of the classics. All the great judges of human existence have said so, from Milton who called reading "conversation with the master spirits" to Virginia Woolf, who imagined the Almighty saying to St. Peter about some newcomers to heaven: "Look, these need no reward. We have nothing to give them . . .They have loved reading." I can only add one thing: it is always time to stop repeating the wise sayings and begin to believe them.

If he knew he would never be caught

Lord Kelvin:

The true measure of a man is what he would do if he knew he would never be caught.

It requires a kind of conjury

From John M. Barry's The Great Influenza.

The greatest challenge of science, its art, lies in asking an important question and framing it in a way that allows it to be broken into manageable pieces, into experiments that can be conducted that ultimately lead to answers. To do this requires a certain kind of genius, one that probes vertically and sees horizontally.

Horizontal vision allows someone to assimilate and weave together seemingly unconnected bits of information. It allows an investigator to see what others do not see, and to make leaps of connectivity and creativity. Probing vertically, going deeper and deeper into something, creating new information. Sometimes what one finds will shin brilliantly enough to illuminate the whole world.

At least one question connects the vertical and the horizontal. That question is "So what?" Like a word on a Scrabble board, this question can connect with and prompt movement in many directions. It can eliminate a piece of information as unimportant or, at least to the investigator asking the question, irrelevant. It can push an investigator to probe more deeply to understand a piece of information. It can also force an investigator to step back and see how to fit a finding into a broader context. To see questions in these ways requires a wonder, a deep wonder focused by discipline, like a lens focusing the sun's rays on a spot of paper until it bursts into flame. It requires a kind of conjury.

New perspectives on reality based on information mediated by symbols

From Mihali Csikszentmihalyi's Creativity.

It seems that every species of living organism, except for us humans, understands the world in terms of more or less built-in responses to certain types of sensations. Plants turn toward the sun. There are amoebas sensitive to magnetic attraction that orient their bodies toward the North pole. Baby indigo buntings learn the patterns of the stars as they look out of their nests and then are able to fly great distances at night without losing their way. Bats respond to sounds, sharks to smell, and birds of prey have incredibly developed vision. Each species experiences and understands its environment in terms of the information its sensory equipment is programmed to process.

The same is true for humans. But in addition to the narrow windows on the world our genes have provided, we have managed to open up new perspectives on reality based on information mediated by symbols. Perfect parallel lines do not exist in nature, but by postulating their existence Euclid and his followers could build a system for representing spatial relations that is much more precise than what the unaided eye and brain can achieve. Different as they are from each other, lyric poetry and magnetic resonance spectroscopy are both ways to make accessible information that otherwise we would never have an inkling about.

Knowledge mediated by symbols is extrasomatice; it is not transmitted through the chemical codes inscribed in our chromosomes but must be intentionally passed on and learned. It is this extrasomatic information that makes up what we call a culture. And the knowledge conveyed by symbols is bundled up in discrete domains - geometry, music, religion, legal systems, and so on. Each domain is made up of its own symbolic elements, its own rules, and generally has its own system of notation. In many ways, each domain describes an isolated little world in which a person can think and act with clarity and concentration.

The existence of domains is perhaps the best evidence of human creativity. The fact that calculus and Gregorian chants exist means that we can experience patterns of order that were not programmed into our genes by biological evolution. By learning the rules of a domain, we immediately step beyond the boundaries of biology and enter the realm of cultural evolution. Each domain expands the limitations of individuality and enlarges our sensitivity and ability to relate to the world. Each person is surrounded by an almost infinite number of domains that are potentially able to open up new worlds and give new powers to those who learn their rules. Therefore, it is astounding how few of us bothers to invest enough mental energy to learn the rules of even one of these domains, and live instead exclusively within the constraints of biological existence.

A link in a chain, a phase in a process

From Creativity by Mihaly Csikszentmihalyi:

According to this view, creativity results from the interaction of a system of three elements: a culture that contains symbolic rules, a person who brings novelty into the symbolic domain, and a field of experts who recognize and validate the innovation. All three are necessary for a creative idea, product, or discovery to take place. For instance, in Vera Rubin's account of her astronomical discovery, it is impossible to imagine it without access to the huge amount of information about celestial motions that has been collecting for centuries, without access to the institutions that control modern large telescopes, without the critical skepticism and eventual support of other astronomers. In my view these are not incidental contributors to individual originality but essential components of the creative process, on a par with the individual's own contributions. For this reason, in this book, I devote almost as much attention to the domain and the to the field as to the individual creative persons.

Creativity is the cultural equivalent of genetic changes that result in biological evolution, where random variations take palce in the chemistry of our chromosomes, below the threshold of consciousness. These changes result in the sudden appearance of a new physical characteristic in a child, and if the trait is an improvement over what existed before, it will have a greater chance to be transmitted to the child's descendants. Most new traits do not improve survival chances and may disappear after a few generations. But a few do, and it is these that account for biological evolution.

In cultural evolution there are no mechanisms equivalent to genes and chromosomes. Therefore, a new idea or invention is not automatically passed on to the next generation. Instructions for how to use fire, or the wheel, or atomic energy are not built into the nervous system of the children born after such discoveries. Each child has to learn them again from the start. The analogy to genes in the evolution of culture are memes, or units of information that we must learn if culture is to continue. Languages, numbers, theories, songs, recipes, laws, and values are all memes that we pass on to our children so that they will be remembered. It is these memes that a creative person changes, and if enough of the right people see the change as an improvement, it will become part of the culture.

Therefore, to understand creativity it is not enough to study the individuals who seem most responsible for a novel idea or a new thing. Their contribution, while necessary and important, is only a link in a chain, a phase in a process. To say that Thomas Edison invented electricity or that Albert Eintstein discovered relativity is a convenient simplification. It satisfies our ancient predilection for stories that are easy to comprehend and involve superhuman heroes. But Edison's or Einstein's discoveries would be inconcievable without the prior knowledge, without the intellectual and social network that stimulated their thinking, and without the social mechanisms that recognized and spread their innovations. To say that the theory of relativity was created by Einstein is like saying that it is the spark that is responsible for the fire. The spark is necessary, but without air and tinder there would be no flame.

Our choices unleash consequences that gain momentum over time

From Kevin Kelly's an article Chosen, Inevitable and Contingent on his site Technium.

Within the borders laid out by inevitable forces, our choices unleash consequences that gain momentum over time until these contingencies harden into technological necessities and become nearly unchangeable in future generations. There's an old story that is basically true: Ordinary Roman carts were constructed to match the width of Imperial Roman war chariots because it was easier to follow the ruts in the road left by the war chariots. The chariots were sized to accommodate the width of two large war horses, which translates into our English measurement as a width of 4' 8.5". Roads throughout the vast Roman empire were built to this spec. When the legions of Rome marched into Britain, they constructed long distance imperial roads 4' 8.5" wide. When the English started building tramways, they used the same width so the same horse carriages could be used. And when they started building railways with horseless carriages, naturally the rails were 4' 8.5" wide. Imported laborers from the British Isles built the first railways in the Americas using the same tools and jigs they were used to. Fast forward to the US Space shuttle, which is built in parts around the country and assembled in Florida. Because the two large solid fuel rocket engines on the side of the launch Shuttle were sent by railroad from Utah, and that line transversed a tunnel not much wider than the standard track, the rockets themselves could not be much wider than 4' 8.5." As one wag concluded: "So, a major Space Shuttle design feature of what is arguably the world's most advanced transportation system was determined over two thousand years ago by the width of two horses' arse." More or less, this is how technology constrains itself over time.