The passions inspired by NAFTA are startling, no doubt about it. Virtues are proclaimed for the measure beyond any reason; fears are voiced that are far more dire than those warranted by any possible outcome. Why all the emotion?

The real reason is that underneath all the dry little arguments, opposition to the North American Free Trade Agreement often involves a subtle but ugly racism.

Many of those who oppose the agreement are people who don't want to think about the modern Mexico-especially the fact that it is just like all the rest of the industrial world. The best illustration I can think of involves a story, now 50 years old, that's still the most revealing I've ever heard about the Mexican-American trade relationship.

The year was 1941. Europe was at war. Mexico City was full of German spies; the embassy was advising all Americans to stay out of Mexico.

Enter Russell Marker. Marker, now 91, is one of the towering figures in the history of American applied science, at least as significant a player as the inventors of nylon, or lasers, or instant photography. He's famous in Germany as the father of synthetic-hormone chemistry.

As a student at the University of Maryland in the early 1920s, Marker discovered that organic chemistry was like "falling off a log." It turned out that he had a rare gift for solving problems that baffled everyone else.

By 1928 his knack for the near-magical synthesis had landed him a job at the Rockefeller Institute. But then Marker became interested in synthesizing human hormones from plants. One Rockefeller scientist was already working on the problem; he announced that it had been proved that it couldn't be done. Marker said he would leave; director Simon Flexner thundered, "No one leaves the Rockefeller Institute if their work is satisfactory!"

So, in the depths of the Great Depression, Marker quit without a Rockefeller recommendation and went to the wilds of central Pennsylvania to teach at Penn State and to do research with a side contract from the big drug manufacturer Parke, Davis & Co. in Detroit.

The need for synthetic hormones was obvious in the mid-1930s; chemicals like estrogen, progesterone and testosterone had come to be seen as keys to the human reproductive process. Pharmaceutical companies spent fortunes collecting the urine of bulls and pregnant mares, from which it isolated tiny quantities of hormones for medicinal purposes. The trouble was that, chemically speaking, nobody knew how to get from here to there.

Then a couple of Japanese researchers sent Marker a sample of an isolate they called diosgenin, which he immediately recognized as a promising source of progesterone with great commercial potential. He quietly set out to find the source himself. At first, he found some roots in North Carolina that contained the compound, but they were uneconomically small, barely the size of a human thumb.

After an extensive search of botanical gardens and books, however, Marker tumbled on the Mexican yam. And, on the banks of a stream between Orizaba and Cordoba, he discovered 300-year-old plants with 500-pound roots just bursting with diosgenin, a single chemical step away from human hormone. The Mexicans called them cabeza de negro; covered with curley dark filaments, they looked from a distance like a human head sticking one-third out of the ground.

Amid high adventure stemming from the anti-American feelings that swirled about him, Marker managed to sneak one plant out of Mexico and back to his lab. Within six months, thanks to a brilliant stroke of chemical intuition-a high-temperature reaction quickly immortalized as "the Marker degradation"-the chemist had produced a more chemically pure progesterone than anyone had ever seen-a Mason jar worth a small fortune.

Marker asked Parke Davis for $10,000 to begin production of progesterone in Mexico, close to the source of the yam. Parke Davis president Alexander Lescohier, a medical doctor, declined. It seemed that a few years earlier he had been taken off a boat near Acapulco with a case of appendicitis. A Mexican hospital nearly killed him, he said. Mexicans couldn't be trusted to get anything right; he'd be damned if he would invest in Mexico.

Well, you've guessed-or can surmise-the rest. Once again, Marker walked out. First he went to several big pharmaceutical companies-Merck, Ciba and Schering-Plough; all agreed that nothing could be done in Mexico. So this time, with a couple of partners, he started a little Mexican company of his own. He called it Syntex, for Synthetics and Mexico.

If you know the chemical industry, then you may know the rest: how Syntex scientists, led by Carl Djerassi, synthesized cortisone in 1951 and then invented the birth-control pill; how Syntex became one of the world's largest manufacturers of pharmaceuticals; how dozens of other chemical companies spun off and grew in Mexico City (some of them founded by Marker himself); how Mexico, which didn't even have a Chemical Society until 1954, grew to be the world's center of the hormone industry.

The rest of Marker's life reads like a page from a story by the novelist B. Traven: He all but disappeared from chemistry, making a comfortable living out of replicating lost rococo silver for collectors and consulting occasionally to intelligence agencies of the U.S. government. But the industry he founded is just one aspect of modern Mexico. He started with a few lab assistants, most of them women, who knew no chemistry and little English. Today Mexican chemists are to be found in the most sophisticated laboratories in the world, from Geneva to Cambridge to Tsukuba.

Now the anti-NAFTA advocates of today, at least a good many of them, are like Alexander Lescohier, the Parke Davis president who didn't like the treatment he received in Acapulco. They know the Mexicans, they say, and Mexicans can't be trusted. They are willing to work for pennies, they say. Mexicans are lazy. They are dirty. They are corrupt. They are not like us.

The evidence for NAFTA speaks for itself. The free trade (and admirably fair trade!) in organic chemicals that Russell Marker engendered required no act of Congress. It made both nations better off.

Mexico is a rapidly growing modern nation, complete with elites and a vast middle class, at home and abroad.

Indeed, the argument about NAFTA is not an economic argument at all; it's about the image, self-confidence and fellow-feeling of the Mexican and American people. Those who insist that it's all about a few thousand jobs, glossing over so great a change as Mexico has made in the last 10 years, are determined lookers at the littlest possible picture.