Theatine moral theologian who strongly influenced the development of casuistry in 17th and 18th centuries; b. Palermo, Sicily, c. 1585; d. Rome, July 20, 1663. Even before taking his vows in the Theatine Order (1630), he had become famous as a counselor in moral matters. urban viii, innocent x, and alexander vii esteemed him highly and named him examiner of bishops. In 1629 Diana published at Palermo a first series of cases, entitled Resolutiones morales. The work's immediate success compelled him to make repeated additions to it; when completed (1659), the 12-volume collection contained 6,000 cases. During the following century it was republished frequently, either in original form or in abridged versions. But when rigorism set in at the end of the 18th century, Diana's reputation waned quickly. Theologians now agree that he had laxist tendencies, and often relied too much on extrinsic proofs to the neglect of moral principles. But his name still exemplifies an epoch in modern casuistry.
Bibliography: a. ingold, Dictionnaire de théologie catholique, ed. a. vacant, et al. (Paris 1903–50) 4.1:734. h. hurter, Nomenclator literarius theologiae catholicae (3d ed. Innsbruck 1903–13) 3:1191–93. r. brouillard, Catholicisme. Hier, aujourd'hui et demain, ed. g. jacquemet (Paris 1947–) 3:739–740.
[r. a. couture]