Antônio Vieira (1608-1697) was the foremost orator in the Portuguese Empire in the 17th century and a defender of Jewish, Native, and black Americans from exploitation and persecution within the empire.

Antônio Vieira was born in Lisbon on Feb. 6, 1608, into a family of modest means. His father obtained a government post in Salvador (Bahia), capital of Brazil, where the family moved in 1614. Antônio studied at the local Jesuit college and proved himself to be a superior student. In 1623 he entered the Society of Jesus and was ordained 11 years later. He taught theology in the Jesuit college, while he earned a reputation as the most brilliant orator in Brazil.

Returning to Lisbon in 1641, Vieira soon became a confidant of King John IV, who sent him on a number of important and delicate diplomatic missions to The Hague, Paris, and Rome. Portuguese diplomacy was...