The Commonitory of Vincent of Lérins, For the Antiquity and Universality of the Catholic Faith Against the Profane Novelties of All Heresies 19
19 Chapter XIX. What we ought to learn from these Examples PL 50, 665
What we ought to learn from these Examples.
[47.] It behoves us, then, to give heed to these instances from Church History, so many and so great, and others of the same description, and to understand distinctly, in accordance with the rule laid down in Deuteronomy, that if at any time a Doctor in the Church have erred from the faith, Divine Providence permits it in order to make trial of us, whether or not we love God with all our heart and with all our mind.
His igitur tot ac tantis caeterisque ejusmodi Ecclesiasticorum exemplorum molibus evidenter advertere, et secundum Deuteronomii leges luce clarius intelligere debemus, quod si quando aliquis Ecclesiasticus magister a fide aberraverit, ad tentationem id nostram fieri Providentia divina patiatur, utrum diligamus Deum an non in toto corde et in tota anima nostra.