The next time you recite the Nicene Creed at Mass, think of today’s saint. For it was Leander of Seville who, as bishop, introduced the practice in the sixth century. He saw it as a way to help reinforce the faith of his people and as an antidote against the heresy of Arianism, which denied the divinity of Christ. By the end of his life, Leander had helped Christianity flourish in Spain...