The Spiritual Exercises (Latin original: Exercitia spiritualia) (composed in 1522-1524) are a set of Christian meditations, prayers and mental exercises, written by Saint Ignatius of Loyola, Spanish priest, theologian, and founder of the Society of Jesus (Jesuits). Divided into four thematic 'weeks' of variable length, it is designed to be carried out over a period of 28 to 30 days. They were composed with the intention of helping the retreatant to discern Jesus in his life, leading him to a personal commitment to follow him. Though the underlying spiritual outlook is Catholic, the exercises can also be undertaken by non-Catholics. The Spiritual Exercises booklet was formally approved in 1548 by Paul III.