On 2 July 1654, Papczyński joined the Piarist Order, newly established in Poland, in their monastery in Podoliniec and was given the religious name of "Stanislaus of Jesus and Mary". He performed the lowliest tasks, cleaning out stables and barns, chopping wood, and washing dishes. He made his second year of novitiate in Warsaw, while studying theology with the Recollect Franciscan friars. Those were the times of the Swedish invasion known as "the Deluge", that made a deep impression on the young seminarian's life. From the perspective of his whole life's experience, he thus described in his testimony one incident from those days: "I confess," he writes, "that I leave this world professing the Catholic faith for which I was ready to pour out my blood during the war with Sweden. One day my companion and I were exiting the Old Town, when a heretic soldier, his unsheathed sword in hand, attacked us near the Dominican Fathers. My companion (even though he was German) fled, and I, falling to my knees, stuck out my neck for the blow. However, by the decree of Divine Providence, I did not sustain any wounds although I was struck three times with great force. Afterward, I felt great pains for an hour and a half because of that."