Devotion to the Sacred Heart is perhaps the most widely practiced of all Catholic devotions, where the heart of Jesus is seen as a symbol of "God's endless and fervent love for all." Evidence of such devotion dates to the 11th and 12th centuries in a number of Benedictine or Cistercian monasteries. It was also widely advocated by the well-known saints Bonaventure (d. 1274) and Gertrude (d. 1302). In this classic 18th-century text by Jean Croiset, the author states his purpose for writing the book in the introduction: "It is hoped that the reflections here made, will help to convince many, of the reasons for practising these holy exercises, and teach them at the same time how to practise them with fruit."

The book is made up of three parts: 1.) Motives, 2.) Means, 3.) Practice. Also included are meditations for each Friday of the year.