“You’re such a fool! Of course I don’t need to see you, if that’s what you mean. You’re not exactly a sight for sore eyes, you know. I need you to exist and not change. You’re like that platinum meter bar they keep in Paris or thereabouts. I can’t imagine that anyone ever actually wants to see it.”
“That’s where you’re wrong.”
“Well I don’t want to see it, not me. I’m just glad to know it exists, that it measures exactly one ten-millionth of the quarter meridian. I think about it every time they measure a room or sell me cloth by the meter.”
“Really?” I answer coldly.
“You know, I could remember you as a merely abstract virtue instead, a sort of limit. You ought to be thankful that I remember your face each time we meet. . . .”
Anny suddenly smiles at me so tenderly that tears fill my eyes.
“I’ve thought about you more often than that platinum meter bar. Not a day goes by that I haven’t thought of you. And I remembered exactly what you looked like, right down to the last detail.”
—JEAN-PAUL SARTRE, Nausea
The baseline of Melun, which Delambre measured in the early spring of 1798, is now known as the N6, a stretch of the national highway that runs northeast out of Melun toward Paris some thirty miles away. In 1882 a party of French geodesers returned to Melun. They checked the masonry pyramids that Delambre had erected at each terminus and rebuilt them as a memorial to his labor. But they did not remeasure his baseline, for fear, it would seem, of impugning the accuracy of the original Archive Meter. Instead, they calculated the length of the baseline indirectly, by triangulation, and found it to be within one centimeter of Delambre’s value. A discrepancy of one centimeter over the course of ten kilometers (six miles) amounts to an error of 0.0001 percent. Whatever progress scientists have made since the eighteenth century, it is still worth pausing to marvel at the level of precision achieved by Delambre and Méchain. And to appreciate what they taught us—both by their efforts and by inadvertence—about error.
It is often said that modern science has “disenchanted” nature, stripping it of demons and divinities, making it mechanistic, devoid of moral lessons and, above all, amenable to explanation. But having disenchanted nature—rendering it fully comprehensible and empty of meaning—science itself could hardly avoid disenchantment as well. In pushing measurement toward the final approach to precision, the savants discovered that error was inevitable, and that dealing with it would mean turning against themselves the same apparatus of disinterested analysis that they had long deployed against nature. In the process, a calling hedged with personal virtue became a career, and a new ethic of error management came to guarantee the accuracy of results. Of course human beings—both lay folk and professionals—will always read moral lessons into nature. And character still counts in science: a scientist’s reputation remains his or her most prized possession. But colleagues now assess one another’s results with dispassionate tools. Error has become a problem that is addressed by a social process.
Today, the memorials at Melun are gone, destroyed in a road accident. The French countryside has been transformed by the world that the metric system helped make possible. The N6 still runs as straight and true as the king’s engineers could make it, a headlong journey through French history. Once it leaves the medieval center of Melun, the N6—named rue General Patton—passes a nineteenth-century brick Catholic school and charity hospital before it runs parallel to a strip mall of shabby bistros and gasoline stations. It then crosses the Cercle d’Europe, a grassy rotary decorated with the flags of the European Community’s member nations, where, on the morning I cycled out of town, a caravan from the Circus Zavetta was encamped, with three Indian elephants grazing on the verge. Beyond the rotary, the highway traverses a stretch of early-third-millennium consumer paradise: a sleek BMW dealership, a gigantic Conforama hypermarché (the French equivalent of Wal-Mart), followed by a series of megastores selling furniture, bathroom tiles, and the like. The scene can be found on the outskirts of a hundred French provincial towns. The Paris media complain about “globalization,” and the tourists marvel at the vegetable stalls on market days, but the French are Europe’s most avid superstore shoppers.
Then the scene changes. Beyond the megastores lie rolling fields of rape, yellow in the sunshine. Soon the fields lick at the roadside, shaded by twin rows of plane trees, quite possibly the same six hundred trees Delambre trimmed to get a clear line of sight down the highway. In the middle of an empty field stands an old inn, “A l’Attaque du Courrier de Lyon,” named after a notorious postal-express robbery which took place nearby in 1796, two years before Delambre conducted his measurements.
Then the scene changes again and the N6 swerves briefly (its only deviation) to pass over the A5 expressway and skirt the main Paris–Lyon TGV high-speed train line. An industrial park, located at this triple junction, ships liquid air and other high-tech products to markets around the world. Once it arrives on the other side of the expressway, the N6 reverts to cobblestones and the highway narrows to pass through the ancient village of Lieusaint, where Delambre’s baseline came to a halt. The town is a remote suburb of Paris, an hour’s commute by rail. The village center consists of a small church, a pizza parlor, and an Arab grocery. Many who live there today are North African immigrants. Some kids were kicking a soccer ball in a field behind a brick wall when I passed through. They asked me about my bike; they told me about life in Lieusaint (which translates as “holy place”). It’s miserable here, they said with a smile.
France has changed in two hundred years. French products go out into the world, and the world has come to France. The world is wrapped in a single metrical language, yet France is still divided by languages and cultures—as is the world.
The creators of the metric system believed that human beings were shaped, first and foremost, by their experience of the world. They wanted citizens to be able to assess their own best economic interest, without which they could never be free. Give people the tools to treat the material world in a rational and consistent manner, they believed, and in time the people themselves would become rational and consistent. They wanted the metric system to create a new kind of citizen, much as we expect the Internet to teach new political virtues to the citizens of the Information Age. Their goal was to make productivity the visible measure of economic progress, and price the paramount variable in exchange. In many ways, their vision has triumphed. The euro, the common currency of much of Europe as of 2002, is a direct heir of the metric system. Nowadays it seems as if price has at last become the measure of all things.
But even the global markets that set prices are social creations governed by human institutions and human desires. And as the labors of Delambre and Méchain amply attest, even our modern impersonal measures are the product of human ingenuity, human passion, and the choices of particular people in particular times and places. So in the end, there is no escaping Protagoras’ 2,500-year-old motto: “Man is the measure of all things.”