Ignacy Polkowski was one of the most outstanding scholars from the Catholic Church in the second half of the 19th century. As a cleric and priest of the Warsaw diocese, later as a priest in Czerniejewo and Lubostroń, and finally as a notary, archivist and custodian of the Bishop's Archives in Krakow, he amazes with the vastness and dynamics of his scientific achievements. His research interests included theology, history and its subsidiary disciplines - archaeology, epigraphy, numismatics, paleography, manuscript studies, incunabulistic studies - and, of course, the history of the Church and literature. A necessary condition for conducting such research was to have a rich collection of manuscripts, incunabula and old prints. Building such a research laboratory required careful observation of the publishing and bookselling market as well as extensive contacts with antiquarians and collectors in all three parts of the then divided Poland. Polkowski's passion for collecting in the years 1861-1888, expressed in numerous purchases and sales, proves his extraordinary skills combined with excellent knowledge. The positions he held in the dioceses of Warsaw, Poznań and Kraków gave him many opportunities to collect handwritten and printed books from church collections. In this way, among other things, he collected a collection which, after his death, was estimated at approximately 20,000-30,000. volumes. In the eyes of his contemporaries, Polkowski's passion as a book collector was also dictated by the desire to save church historical book collections and private libraries and archives from dispersion and removal.