In 1592, at 35, Calasanz moved to Rome. He hoped to further his ecclesiastical career and secure some kind of
benefice. On Christmas Day in 1598, the
Tiber flooded its banks to historic levels, reaching an additional depth of nearly 20 m (65 ft) above its normal level. The devastation was widespread. Hundreds of the already poor families who lived along the river's banks were left homeless and without food. The death toll was estimated at about 2,000. Calasanz threw himself into the response, joining a religious fraternity dedicated to helping the poor, and began to help in the cleaning up and recovery of the city. In 1600, he opened his “Pious School” in the center of Rome and soon there were extensions, in response to growing demands for enrollment from students.
Pope Clement VIII began making an annual contribution and many others gave their financial support to the work so that in a short time Calasanz had about 1,000 children under his charge. In 1602, he rented a house near
Sant'Andrea della Valle, commenced a community life with his assistants, and laid the foundation of the Order of the Pious Schools or Piarists. In 1610, Calasanz wrote the
Documentum Princeps in which he laid out the fundamental principles of his educational philosophy. The text was accompanied by regulations for teachers and for pupils. 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. 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. During one of the city's many outbreaks of plague, 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, too, he established 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 modern abbreviation "Sch. P." following the name of the Piarist stands for
Scholarum Piarum, Latin for "of the Pious Schools". The Order's Constitutions were approved by Gregory XV 1621, and the order was granted all the privileges of the
mendicant orders, Calasanz being recognised as
superior general. The Order of the Pious Schools was thus the last of the religious Orders of solemn vows approved by the Church. The Piarists, as do many religious, profess vows of
poverty, chastity, and obedience. In addition, according to the wishes of St. Joseph, members of the Order also profess a fourth vow to dedicate their lives to the education of youth. ==Educational ideas==