RETREAT may be defined as a limited period of isolation during which an individual, either alone or as part of a small group, withdraws from the regular routine of daily life, generally for religious reasons. Retreats are one of the commoner practices in the religious life of nearly all peoples, although they are often restricted to a determinate type or class of persons: those preparing for initiation (e.g., into the adult life of a clan, into a religious group, or into some public office of a religious nature), those undergoing a process of conversion, those in search of a religious vocation, or those seeking a periodic renewal of their spiritual lives. During this period, retreatants interrupt their ordinary routine, break off regular social relationships, and (except for those who already live in monasteries or the like) withdraw into a solitary place or to a special building set...