Leander was born to Roman parents somewhere around the year 534 in Carthage. When Leander was a young man, his family moved to Seville. Leander became a Benedictine monk and in 579 was made Bishop of Seville. He also established a school, which became known as a center of learning and orthodoxy. Leander became a great defender of the faith against Arianism, which was a heresy that denied the Divinity of Christ. During this time he also befriended Princess Ingunthis and assisted her in her attempts to convert her husband to Christianity. Her husband was the son of Leovigild, the Arian King of the Visigoths, and Leovigild was infuriated by his son's conversion.
Leovigild sent Leander into exile, so from 579 to 582 Leander resided in Byzantium. While in exile, he composed many important writings against Arianism and met the future Pope Gregory the Great. They developed a close friendship and it was Leander who encouraged Gregory to write his famous commentary on the Book of Job, called the Moralia. Over the years, Leander and Gregory continued to correspond with each other.
Leovigild had his own son, Hermenegild, a Christian convert, put to death in the year 585, and Leovigild died in 589. Leander returned to Seville under the reign of King Reccared and continued his life's work of promoting the true faith and fighting against Arianism. In 589 he presided over the third local Council of Toledo where many moral reforms were brought about. Also at this Council, the consubstantiality of the three Persons of the Trinity was decreed. Through Leander's wisdom and persistent defense of the faith, the Visigoths and the Suevi were led back to the Church.
Leander is responsible for introducing the Nicene Creed at Mass. Leander died around the year 600 and was succeeded as Bishop of Seville by his brother, Isidore, who also was later canonized.
St. Isidore wrote this of his saintly brother: "This man of suave eloquence and eminent talent shone as brightly by his virtues as by his doctrine. By his faith and zeal the Gothic people have been converted from Aryanism to the Catholic faith."
Saint Leander, pray for us that we will always seek truth, and never shy away from defending it. In Christ's Name, we pray. Amen