The rejection of the /Sentences/ in favour of the /Summa/, and the reform decrees of the Council of Trent gave a new impetus to the study of moral theology during the sixteenth and seventeenth centuries. Most of the great writers of this period, Gregory of Valencia (1550-1603), Vasquez (1549-1604), Lessius (1554-1623), Banez (1528-1604), Medina (1527-81), Sanchez (1550-1610), Saurez, and De Logo devoted special attention to the underlying principles of moral theology, and in some cases to their practical application. The /De Poenitentia/ and the /Responsa Moralia/ of De Lugo served as models of what might be called mixed treatment, partly scientific and partly casuistical. The /Theologia Moralis/ of the Jesuit writer, Paul Laymann (1574-1635), the /Instructio Sacerdotum/ of Cardinal Toledo and the /Medulla Theologiae Moralis/ of Hermann Busenbaum (1600-68), which went through forty editions in his own lifetime, may be cited as examples of this method. The controversy regarding Probabilism did not assume a serious aspect till the rise and condemnation of Jansenism. During this period the enemies of the Jesuits pointed to the approval given to Probabilism by the Fathers of the Society as a proof of the laxity of view introduced by Jesuit theologians. Whatever may be said of the system, one thing is certain, namely, that the Jesuit theologians were not the first to put it forward. It was followed in practice long before the institution of the Society of Jesus, was enunciated clearly enough as a theory by the Spanish Dominican Bartholomew Medina (1527-81) and was adopted, at least in their solutions of particular cases, by most of the great writers during the latter half of the sixteenth and the first half of the seventeenth centuries. Amongst the most notable writers on ascetical theology of this period were St. Ignatius of Loyola, the author of the /Spiritual Exercises/, St. Teresa (1515-82) the zealous reformer of the Carmelites, St. John of God (1495-1550) the founder of the Brothers of St. John of God, the Dominican Louis of Granada (1504-88), St. Francis de Sales (1567- 1622), the two Jesuit writers Alphonsus Rodriguez (1526-1616) and Louis de Ponte (1554-1624), and Jean Jacques Olier (1608-57) the founder of the Sulpicians.