This article describes a unique early seventeenth-century project at the monastery of Santa Prassede in Rome to adapt and prove the validity of Ptolemaic astrology by an empirical study of the lives and deaths of both eminent personages and common people in the neighborhood. In contextualizing this effort, it focuses on the life and career of the astrologer Orazio Morandi, abbot of the monastery and one-time general of the Vallombrosa order. On the basis of the activities of Morandi and the other monks, it then draws some conclusions regarding the fortunes and misfortunes of the Ptolemaic astrological tradition in the period.