More popular during the Middle Ages was Severus's Life of St. Martin, as were also the dialogues and letters which relate to the same subject. These works did much to establish the great reputation which that wonder-working saint maintained throughout the Middle Ages. The book is not properly a biography, but a catalogue of miracles, told in all the simplicity of absolute belief. The power to work miraculous signs is assumed to be in direct proportion to holiness, and is by Severus valued merely as an evidence of holiness, which he is persuaded can only be attained through a life of isolation from the world.