Modern devotion to the Sacred Heart is closely associated with the name of St. Margaret Mary and popular practices such as the Nine Fridays and the Holy Hour, and its beginnings are not so well known. Yet it originated not at Paray-le-Monial but in the centres of medieval contemplative life, especially in the Benedictine, Cistercian and Carthusian monasteries. St. Gertrude, the famous mystic of Helfta, is perhaps its most striking representative.

Little is known of her outward life, which is not surprising, for she entered her convent at the age of five, never to leave it. She was long regarded as its abbess, and most pictures still represent her assuch. But, according to modern scholars, this view was based on an erroneous identification of her with her namesake, Gertrude of Hackeborn, who governed the monastery during the Saint’s lifetime. It is even doubtful whether she was a Cistercian or a Benedictine. The main source of our knowledge of her are her Revelations, written in Latin, which, after her death, remained hidden for a long time. One manuscript, however, seems to have been in the possession of Master Eckhart, and the Dominicans were the first to defend her doctrine, and translated her works in 1505. Their devotion was shared by the Carthusians, especially by Justus Lanspergius, who, attracted by her cult of the Sacred Heart, became one of her most ardent disciples.

Of the five books of her Legatus Divinae Pietatis, to give it its Latin title, only the second is written by herself, the remaining four are compiled from her notes by one of her nuns.