Over three months, he gave himself a solo tutorial on modern factory farming. "I read a dozen books about how animals are raised in this country," he says, "going all the way back to Peter Singer's Animal Liberation in 1975. The more I read, the more I was interested in it. I said, Damn, these people are right. This is terrible."

Mackey did two things. He changed his vegetarian diet to vegan (he no longer eats food produced from animals, including dairy products). And he sent Ornelas an email telling her she was right -- not just about ducks, but about chickens, pigs, and cows. Mackey wrote that Whole Foods would immediately begin using its influence and buying power to demand that the meat it sells comes from animals that have been treated with a measure of dignity before being slaughtered. He invited Ornelas to help.

Sitting in his office in 2004, he says without hesitation, "Twenty years from now, factory farms will be illegal in the United States."