The Spiritual Exercises were developed by St. Ignatius of Loyola in the 1520s as a way for people to deepen their relationship with God through meditation and prayer. Though initially met with suspicion by Church officials who thought they were linked to the Protestant Reformation, the Exercises gained popularity and approval. They have been a cornerstone of the Jesuit order for 400 years and are still used today in retreats of flexible length, adapted from St. Ignatius' original vision of a 30-day format.