Among manuals on the life of prayer, the chapters on prayer from Jean-Nicholas Grou's School of Jesus Christ stand out as one of the best short expositions of the essence of prayer that have ever been written. Like such other great writers on prayer as William Law, Henry Martyn and Charles de Foucauld, Grou emphasises the importance of mental discipline for the healthy life of the soul. These simple but effective instructions are the ripe fruit of the author's long life of prayer and meditation. Translated by Joseph Dalby.