CALVINUS, Justus. — Controversialist, born in Wetter (Hessen) in May 1572, died in Mainz between 1616 and 1621. While attending the theology course in Heidelberg, he happened to read the *Annales* of Cesare Baronio, which were then being published. This reading and his study of the Fathers around the year 1600, the very year of his conversion, enlightened him and drew him into the orbit of Catholicism through the correspondence then deliberately initiated between him, a seeker of truth, and Baronio, who became his amiable, patient, and solicitous spiritual master and guide. This correspondence now constitutes a precious relic in the Vallicelliana Library in Rome (cf. Vallicellian codex Q. 47, fol. 117 ff.).
Having gone to Rome to visit the Eternal City and his spiritual benefactor (1601), C. was baptized in the Lateran Basilica by Clement VIII himself, with Cardinal Baronio as his sponsor. Out of deferential gratitude, Justus C. then wished to adopt the surname Baronio as well. The cardinal showered him with attentions, admitted him among his household, and kept him with him for four months. Upon his return home, he provided him with a letter of recommendation to the Elector Archbishop of Mainz. It begins thus: “He who came from Mainz to Rome as Justus C. now returns from Rome to Mainz as Justus Baronio.”
The new convert earned his degree at the Italian universities of Perugia and Siena, and then, back in his homeland, recounted his conversion in a volume entitled *Apologia* (Mainz 1601). He also wrote *Proscriptionum adversus haereticos... Tractatus* (ibid. 1602 and 1756) and *De falso Jubilaeo Wittembergesi adversus Aegidium Junium Lutheri discipulum*, and upon the death of Cardinal Baronio, a funeral oration in his honor which he sent to Nicola Serrario, the Jesuit from Lorraine and friend of Baronio himself.