In 1737, on Monte Argentario (Grosseto), he opened the first House of the Congregation. In 1741 Pope Benedict XIV approved the Rule with a rescript and again in 1746 with a Pontifical Brief. In 1769 Clement XIV, who had a great affection for Paul, endorsed the Institute.
In 1771, after much suffering, Paul joyfully received news of the inauguration of the first Passionist monastery for cloistered nuns in the city of Tarquinia (Viterbo, Italy).
In 1773 he opened the Retreat of Saints John and Paul on the Caelian Hill in Rome, the gift of Clement XIV, who was a protector and incomparable benefactor of the Congregation. In 1775 he rejoiced in the final approbation of the Rule by Pius VI.
Despite having an episode of mystical marriage in his youth, Paul experienced heartbreaking spiritual dryness for about fifty years. He lived through many difficult trials that resulted in him being called “the prince of the destitute“. He realized perfectly his desire to “be crucified with Jesus”. And he, the Mystic of the crucified, became the one who was mystically crucified.
In the century of the enlightenment and of the deification of reason, he pointed out the way of salvation in the weakness and folly of the Cross — the cross of human wisdom and the strength of the power of God.