In the last century St. Catherine of Siena, an Italian lay woman and mystic of the fourteenth century, was named first a Doctor of the Church and then one of six patron saints of Europe. This recognition of her life and spirituality has been accompanied by increased interest in her writings. Obeying the Truth addresses the key concept of discretion in Catherines spiritual works. This concept, synonymous with prudence, interacts on many levels with crucial aspects of her teaching. Grazia Mangano Ragazzi argues that discretion, to which Catherine dedicates several passages in her writings, is a helpful, even decisive, tool for interpreting the whole edifice of the saints spirituality. Providing a textual analysis of discretion in Catherines major works, Mangano Ragazzi situates Catherine historically through comparison with her predecessors: Augustine, Cassian, Benedict, Gregory the Great, Bernard, Richard of St. Victor, and Thomas Aquinas; and some contemporaries: Domenico Cavalca, Bridget of Sweden, John Colombini, and Raymond of Capua. She goes on to demonstrate how discretion unifies Catherines spiritual reflection. The book includes a scrupulously selected bibliography of works in English, Italian and French. This is both a focused monograph on discretion and an ideal introduction to the saints writings. Catherines insistence that the virtuous life is a pre-requisite for any genuine spiritual experience is a warning that is more necessary today than ever.