A prolific artist, Chagall excelled in the European tradition of subject painting and distinguished himself as an expressive colorist. His work is noted for its consistent use of folkloric imagery and its sweetness of color, and it is characterized by a style that, although developed in the years before World War I, underwent little progression throughout his long career. The 'Jerusalem Windows' lithographs represented the twelve sons of the Patriarch, Jacob, from who came the Twelve Tribes of Israel. Chagall's images are populated by floating figures of animals, flowers, fish, and numerous Jewish symbols. The dominant colors used in each lithograph are inspired by those blessings as well as by the description of the breastplate of the High Priest in Exodus 28:15, which were colored gold, blue, scarlet, and purple, and contained 12 gems including turquoise, emeralds, sapphires and lapis lazuli. Printed by Mourlot in 1962, these series of lithographs was executed by Chagall in preparation for his famous stained-glass windows for the synagogue at the Hadassah-Hebrew University Medical Center in the Judaean Hills.