Complex sentence: His "Skarga's Sermon" finished in May 1864 and displayed in the gallery of the Kraków Society of Friends of Fina Art ("Towarzystwo Przyjaciół Sztuk Pięknych w Krakowie"), which gained him much publicity.
Split into simpler sentences: His "Skarga's Sermon" finished in May 1864. It was displayed in the gallery of the Kraków Society of Friends of Fine Art ("Towarzystwo Przyjaciół Sztuk Pięknych w Krakowie"), which gained him much publicity.