Denis Pétau, also known as Dionysius Petavius (1583-1652), was a French Jesuit theologian from Orléans. He received his initial education locally and later pursued studies at the University of Paris, where he distinguished himself by defending theses for the degree of Master of Arts in Greek rather than Latin. Following theological lectures at the Sorbonne, he secured the chair of philosophy at Bourges based on the recommendation of Nicolas Ysambert. Pétau’s scholarly pursuits led to a friendship with Isaac Casaubon, the royal library’s librarian, where he dedicated his spare time to studying ancient Greek manuscripts. Pétau was ordained as a deacon in Orléans in 1603 and received a canonry soon after.

In 1605, Pétau joined the Society of Jesus, subsequently teaching rhetoric at various institutions, including Reims (1609), La Flèche (1613), and the Collège de Clermont (1618). His academic contributions include correspondence with Fronton du Duc on John Chrysostom’s works. After a brief lecturing stint in Madrid in 1629, at the invitation of Philip IV, and a second trip to Rome in 1639, where he declined the offer of cardinalship from Pope Urban VIII, Pétau dedicated the remaining years of his life to his magnum opus, the Dogmata theologica. He concluded his teaching career at the age of sixty but continued as a librarian in Paris until his death. One of the Moon’s craters is named Petavius in his honor.