Order of the Pious Schools or Piarists. In 1610, Calasanz wrote the Document Princeps in which he laid out the fundamental principles of his educational philosophy. The text was accompanied by regulations for teachers and for students. On September 15, 1616, the first public and free school in Frascati was started up on Calasanz' initiative. One year later, on March 6, 1617, Pope Paul V approved the Pauline Congregation of the Poor of the Mother of God of the Pious Schools, the first religious institute dedicated essentially to teaching, by his brief "Ad ea per quae." On March 25, 1617, he and his fourteen assistants received the Piarist habit and became the first members of the new congregation. The habits were paid for by the Cardinal Protector 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. Emphasizing 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 graves of the Roman martyrs. During one of the city's repeated plagues, a holy rivalry existed between him and St. Camillus in aiding the sick and in personally carrying away for burial the bodies of those who had been stricken. On account of his heroic patience and fortitude in the midst of trouble and persecution, he was called a marvel of Christian courage, a second Job. During the following years, Calasanz established Pious Schools in various parts of Europe. In October 1628 he was a guest of the Conti di Segni family in Poli and there he founded the Pious Schools. After convincing the pope of the need to approve a religious order with solemn vows dedicated exclusively to the education of youth, the congregation was raised to that status on November 18, 1621, by a papal brief of Pope Gregory XV, under the name of Ordo Clericorum Regularium Pauperum Matris Dei Scholarum Piarum (Order of Poor Clerics Regular of the Mother of God of the Pious Schools). The abbreviation "Sch. P." following the name of the Piarist stands for Scholarum Piarum, Latin for "of the