In a famous debate held at Valladolid on the Yucatan Peninsula in 1550, Las Casas argued for the equality and freedom of the Native Americans. The only way to convert them, he said, was by peaceful preaching of the Word and by the example of holy living. His opponent was a theologian, Juan Gines de Sepulveda, who used Aristotle’s argument that certain peoples are by nature born to slavery. “The Spanish,” he said, “are as much above the Indians as man is above the ape.” So despite Las Casas’s best effort, Christian imperialism and slavery continued in the New World.