St. Peter and St. Paul (1st c.) were the foremost Apostles of Jesus Christ; St. Peter was the leader of the Twelve, while St. Paul followed Christ after His ascension into heaven. Together the two saints are the founders of the Church in Rome through their apostolic preaching, ministry, and martyrdom in that city. They are the solid rock on which the foundation of the Catholic Church is built,...

St. Irenaeus of Lyons (c. 125 - 203 A.D.) was born in Asia Minor at a time when the direct memory of the Apostles was still alive. He was well educated in Sacred Scripture, theology, philosophy, and literature. He became an astute disciple of St. Polycarp, who himself was a disciple of St. John the Evangelist, one of the Twelve Apostles who belonged to Jesus' inner circle. St. Irenaeus is...

St. Cyril of Alexandria, Bishop and Doctor of the Church, was born at Alexandria, Egypt. He was nephew of the patriarch of that city, Theophilus. Cyril received a classical and theological education at Alexandria and was ordained by his uncle. He succeeded his uncle Theophilus as patriarch of Alexandria on Theophilus' death in 412. Cyril wrote treatises that clarified the doctrines of the...

St. William of Vercelli was born in 1085 into a noble family of Vercelli in northwest Italy and brought up by a relation after the death of his parents. He undertook a pilgrimage to Santiago de Compostela. On his pilgrimage to Compostela, William asked a blacksmith to make an iron implement that would encircle his body and increase his suffering, and he wore it throughout the pilgrimage....