(1) A "Commentary upon the Psalms", concise but excellent for its method, clearness and solidity. He especially developed the spiritual sense, according to the interpretations of St. Jerome, St. Augustine, Cassiodorus and Peter Lombard. This commentary, which was very popular in Germany in the Middle Ages, has passed through numerous editions, of which the first dates from 1491, and that by Montreuil-sur-Mer is from 1891. (2) The "Vita Christi", his principal work, is not a simple biography as we understand such to-day, but at once a history, a commentary on the Gospels with large texts borrowed from the Fathers, a series of dogmatic and moral dissertations, of spiritual instructions, meditations and prayers, in relation to the life of Christ, from birth to His Ascension. It has been called a summa evangelica, so popular at that time, in which the author has condensed and resumed all that over sixty writers had said before him upon spiritual matters.
Sr Bodenstedt mentions Ludolph's particular debt to Pseudo-Bonaventure's Meditationes Vitae Christi, some believe is Pseudo-Bonaventure is Thomas a Kempis . Bodenstedt argues that Ludolph also follows Ps.-Bonaventure in his visual method of meditation Nothing shows better the great popularity of the "Vita Christi" than the numerous manuscript copies preserved in libraries and the manifold editions of it which have been published, from the first two editions of Strasburg and Cologne, in 1474, to the last editions of Paris (folio, 1865 Published by Victor Palme(heavily criticised by Father Coleridge SJ see below) and 8vo, 1878). It has besides been translated into Catalonian (Valencia, 1495, folio, Gothic), Castilian (Alcala, folio, Gothic), Portuguese (1495, 4 vols., folio), Italian (1570), French, "by Guillaume Lernenand, of the Order of Monseigneur St. François", under the title of the "Great Life of Christ" (Lyons, 1487, folio, many times reprinted), by D. Marie-Prosper Augustine (Paris, 1864) and by D. Florent Broquin, Carthusian (Paris, 1883). St. Teresa and St. Francis de Sales frequently quote from it, and it has not ceased to afford delight to pious souls, who find in it instruction and edification, food for both mind and heart.
Ludolph's De Vita Christi is mentioned in almost every potted biography of St Ignatius of Loyola. St Ignatius read it whilst recovering from the cannon-ball wound after the siege of Pamploma in an edition in Castilian. Ludolph proposes a method of prayer which asks the reader to visualise the events of Christ's life (known as simple contemplation). In his commentary on the Gospel for the Feast of Saint Mary Magdalen, the story where Mary the sister of Lazarus, comes into the house of the Pharisee where Jesus is eating, and washes his feet with her tears and then dries his feet with her hair, Ludolph repeatedly urges the reader to see (ie visualise ) the scene of the washing etc. He also has beautiful insights into the humanity and attractiveness of Jesus. He explains why Mary the public sinner overcame her shame and entered the house of the Pharisee by noting that the Pharisee was a leper and disfigured from the disease. St Mary Magdalen could see from the fact that Jesus was prepared to eat with a leper that he would not reject her.
This simple method of contemplation outlined by Ludolph and set out in De Vita Christi in many of his commentaries on the gospel stories that he chooses it can be argued influenced the Spiritual Exercises of St Ignatius of Loyola. Indeed it is said that St Ignatius had desired to become a Carthusian after his pilgrimage to Jerusalem but was dissuaded by a Carthusian Prior. To this day members of the Society of Jesus may enter a Charterhouse. If their vocation there does not work out they may return to the Society of Jesus without penalty. This closeness between the Carthusians and Jesuits is arguably due to the great influence of Ludolph of Saxony's De Vita Christi on the future founder of the Society of Jesus.
Michael Foss is dismissive of the influence of Ludolph on the Exercises of St Ignatius saying "The Exercises show a bit of Ludolph" and then writing of St Ignatius recovering from the cannon would at the Castle of Loyola he says St Ignatius "Bored, as only a man of action can be when driven to bed, he was driven by desperation to a few unappetising volumes that the Castle of Loyola offered. he found a Castilian translation of the long, worthy and popular Life of Christ by a certain Ludolph of Saxony a 14th Century writer.
Father Henry James Coleridge SI, the grand-nephew of Coleridge in his article of 1872 in The Month in the Review of Famous Books section of that periodical urges future translators of the Vita Christi to be cautious with the Folio edition of the Vita Christi published by Palme in 1865 since it is marred by poor punctuation and based on a poor manuscript