Berthold of Ratisbon was a Franciscan of the monastery of Ratisbon and the most powerful preacher of repentance in the thirteenth century.
He was born about 1210. He was probably a member of a well-to-do middle-class family of Ratisbon named Sachs. The excellence of his literary training is proved by his sermons which show more than common acquaintance with the ancient classics. From his knowledge of the usages of secular life, it may be inferred that he was of mature age before he entered the monastery. The first fixed date in Berthold's life is 1246, when the papal legate appointed him and David of Augsburg inspectors of the convent of Niedermünster. One of his contemporaries, the Abbot of Niederaltaich, a reliable historian, speaks in 1250 of the great reputation that Berthold had in Bavaria as a preacher.
Four years later the missionary trips of this preacher extended as far as the valley of the Rhine, Alsace and Switzerland. During the next ten years Berthold's apostolic labours led him eastward into Austria, Moravia, Bohemia and Silesia. In 1263 Pope Urban IV appointed him to preach the Crusade and Albert the Great was designated as his assistant. When speaking to Slavonic audiences, Berthold naturally employed an interpreter, just as St. Bernard, in his day, made use of an interpreter in Germany. Notwithstanding any difficulties that might arise as to speech, wherever he went Berthold exerted an extraordinary power of attraction over his hearers so that the churches were not able to hold the great crowds of plain people who came from all quarters to his services, and he was often obliged to preach in the open air. When this was the case, a pulpit was generally arranged under the spreading branches of a linden tree. Long after his day "Berthold's linden" was to be seen at Glatz.