Liber Extra
Canon law (Decree of Gratian, Decretals of Gregory IX) recognized it as a punishment for ecclesiastics; even as late as the sixteenth and seventeenth centuries, it appears in ecclesiastical legislation as a punishment for blasphemy, concubinage and simony. Though doubtless at an early date a private means of penance and mortification, such use is publicly exemplified in the tenth and eleventh centuries by the lives of St. Dominic Loricatus and St. Peter Damian (died 1072). The latter wrote a special treatise in praise of self-flagellation; though blamed by some contemporaries for excess of zeal, his example and the high esteem in which he was held did much to popularize the voluntary use of a small scourge known as a discipline, as a means of mortification and penance. From then on the practice appeared in most medieval religious orders and associations.