Denis (better known under the Latinized form of his name, Dionysius Petavius), a French Jesuit of great erudition, was born at Orleans in the year 1583. To the study of the belles-lettres he joined that of the mathematics; and afterwards applied himself to a course of philosophy, which he commenced in the college of Orleans, and finished at Paris. He subsequently maintained theses in Greek, which was as familiar to him as Latin; and the Latin, it is said, he understood better than he did his vernacular language. When he was pretty well advanced in his studies, he had free access to the king's library, which he often visited on account of the Latin and Greek manuscripts. Amongst other advantages which attended his literary pursuits, may be reckoned the friendship of Isaac Casaubon, whom Henri IV. called to Paris in 1600. It was at Casaubon's instigation that Petavius, though then very young, undertook an edition of the works of Synesius, in which he corrected the Greek from the manuscripts, translated what yet remained to be translated into Latin, and wrote notes upon the whole. He was only nineteen years of age when he was made professor of philosophy in the university of Bourges; and he spent the following years in studying the ancient philosophers and mathematicians. In 1604, when Morel, professor of Greek at Paris, published the works of St Chrysostom, some part of Petavius' labours on Synesius were added to them; and from the title we learn that he then took the name of Petas, which he afterwards changed into Petavius. His own edition of the works of Synesius did not appear till the year 1612. He entered into the Society of the Jesuits in 1605, became a zealous advocate of the Church of Rome, and rejoiced in criticising and assailing its adversaries. He was bitter against Joseph Scaliger; nor did he even spare his friend Casaubon whenever the latter came in his way. Muratori regarded Petau as "the restorer of dogmatic theology." He excelled likewise in chronology. His great work on that subject, entitled Rationarium Temporum, is an abridgment of universal history from the earliest times till the year 1632, arranged in chronological order, with references to proper authorities; and it was improved by Perizonius and others, who made several additions to it after his death. Petau died at Paris in 1632, aged sixty-nine.