ETHICS the contract morally licit Henceforth the prohibition on usury was a dead letter among Roman Catholics Mysticism and Stoicism The heyday of casuistry was the century from 1550 to 1650 During that period volumes of casuistry were not, of course, the only guides to life that were published On the one hand, there were many manuals of devotion which included practical moral advice; on the other hand, some writers urged the merits of ancient ethical texts As examples of these two tendencies we may consider St John of the Cross and Rene´ Descartes St John of the Cross (1542–91), the spiritual director of St Teresa of Avila, who reformed the Carmelite order, was a poet and mystic His work The Dark Night of the Soul describes the long and painful ascent which leads to union with God He describes the ecstasy of the goal in terms of incomprehensible rapture, but he makes clear that the way towards it is through suVering and self-discipline First one must enter the dark night of the senses; but this is only a kindergarten of preparation for the dark night of the soul, which is itself only the Wrst stage of the mystical ascent It is thus that he sets out the Wrst steps of the spiritual life: Strive always to prefer, not that which is easiest, but that which is most diYcult; Not that which is most delectable, but that which is most unpleasing; Not that which gives most pleasure, but rather that which gives least Not that which is restful, but that which is wearisome In order to arrive at having pleasure in everything, Desire to have pleasure in nothing In order to arrive at possessing everything Desire to possess nothing In order to arrive at being everything, Desire to be nothing St John’s treatise was the most severe of sixteenth-century devotional guides, and was clearly addressed to a cloistered minority But similar teaching, in a more emollient form, was presented by the French bishop St Francis de Sales, in his Introduction to the Devout Life (1608), the Wrst manual of piety aimed at lay people living a secular life in the world 251