The post-Tridentine reform of nuns forced even members of the Third Order to adopt a strictly monastic, closed lifestyle. The Dominicans, who began reforming their Third Order communities in this direction, nevertheless could not believe that the way of life adopted by St. Catherine of Siena and many other saints was unworthy of continuing. In effect, they tried to save as much of the "freer form of religious life in the Church" as possible. In the Rule for the Sisterhood of the Third Order in Poland, published in 1616, its alleged author, Master Nicholas, attempts to solve this problem by insisting on enclosure and a strict interpretation of monastic vows, exempting nuns from choral duties. The clause remained unenforceable in practice because the Dominican communities in question (and there were five of them in Poland at that time) did not have their own churches. So the nuns had no choice but to attend Holy Mass. in the local Dominican church, even if it violated the new regulations. However, this article is not so much about the effects of the new code, but about the Rule of Master Nicholas. The author of the article is convinced that the book in her possession is the only surviving copy of this work. There is no doubt that this important document on post-Tridentine law and mentality deserves to be reprinted.