foreign wars impeded its growth; it was not till the thirteenth century that an important chronicle was written in Polish by the Cracow bishop Vincent Kadlubek, who ended his days as a Cistercian monk at Mogila (1223). He was followed by the Posen chroniclers Boguchwal and Baszko; a Polish Dominican living in Rome, Martinus Polonus, compiled a Chronicle of,the Popes and Emperors. In Rome also there lived, about 1230, in the court of Pope Innocent V, an eminent Polish man of science, called Vitellio; his work De Perspectiva was based on observations made in Poland. A careful study of the Greek and Arabian authors led him toward formulating in a system the laws of optics, and by these fundamental principles he made an important contribution to the theory of perspective landscape painting, for which he opened entirely new horizons.
Besides the illuminated MSS., pictures began early to be imported both from East and West. The worship of the Virgin Mary having been awakened among the Polish people, the merchants brought Madonna pictures from abroad, richly decorated with gold and jewels; mosaics also were introduced: of these, a Byzantine one, of the twelfth century, showing a deeper sense of the beauties of colour, is preserved in St. Andrew's Church. Of the state of applied art in this Romanesque period, evidence is given by the coins and seals produced at Cracow, which are most vivid illustrations of our medieval civilization. The oldest inventories of the Cathedral Church, dated 1101 and 1110, bear witness to the use of numerous costly implements and liturgical apparel. Among the oldest of those still preserved in the Cathedral treasury is the mitre of St. Stanislas, made of white silk, in lozenge pattern and adorned by a cross made of two blue bars. The profusion of gold, jewels, and gems, with which it is beset besides, is contrary to tradition and points to a later date (thirteenth century). Oriental origin is probable for a silver reliquary of Saracen workmanship; it dates from the twelfth century and was probably presented to the Cathedral by Henry Duke of Sandomir, a son of Boleslaus III, who had taken part in a crusade. He brought to the treasury of Cracow Cathedral this
