Justiniani, who with his own hands invested Joseph Calasanz in the chapel of his palace. They were the very first priests to have as their primary ministry teaching in elementary schools. Emphasising love, not fear, St. Joseph wrote: "if from the very earliest years, a child is instructed in both religion and letters, it can be reasonably hoped that his life will be happy."

While residing in Rome, Joseph endeavored to visit the seven principal churches of that city almost every evening, and also to honor the tombs of the Roman martyrs.