In a treatise published in 1522 Lucas attacked Luther's teaching on several points, but on receiving a conciliatory answer from the great German reformer he decided on entering into negotiations with him. He sent a member of the Unity, Brother Roh[82] or Horn, to Wittenberg with copies of several of his works. Luther does not seem to have had a very clear idea of the identity of the community which wished to enter into relations with him, for he addressed his answer to "his dear nobles and friends the brethren called Waldenses living in Bohemia and Moravia." The contents of the letter appear to have displeased Lucas, who wrote several treatises for the purpose of "strengthening" the brethren against the teaching of Luther. Lucas, indeed, somewhat later sent a second messenger to Wittenberg, but the disagreement continued, and subsequently a complete rupture took place. To the end of his life Lucas continued to labour at the reorganisation of the Unity. One of his latest and most important works was his _Zpráva Kněžka_ ("Instruction for the Clergy of the Unity"), published in 1526; he died two years later. It has already been mentioned that Brother Lucas was a voluminous writer. Dr. Jireček in his biography published in 1875 enumerates sixty-eight works of Lucas, some of which, it is true, are known only by repute and have not been preserved. Since the appearance of Dr. Jireček's book, Dr. Goll has discovered works of Lucas that are not included in his list. Among the works of Brother Lucas known now only by name but enumerated in Dr. Jireček's list is an "Answer to the ten articles of Master Jerome Dungesham[83] of Oxford, (written) against the apology of the Brethren published in 1514." The first work of Lucas, was as already mentioned, his _Barka_ or "Bark." This work too was believed to be lost, but within the last years Dr. Goll has discovered a MS. which contains this once celebrated work of Lucas. The allegorical name of the book is thus explained by the author. He tells us that in the first part of his work the bark signifies the Unity, and that it is his purpose to explain out of what planks it is constructed, what are its requirements, who is its captain and guide, and what is the destination of its course. In this first part of the work the captain is Jesus Christ. The second division of the book deals with "The Bark of Antichrist," with the foolish and misguided people who occupy it, and with the weighty reasons for flying from that bark, the course of which leads to perdition. Like so many Bohemian works of this period, the "Bark" treats mainly of Antichrist. It is interesting as being very similar, and in parts identical, with one of the ancient books of the Waldenses. It undoubtedly throws some light on the obscure question of the relations between the Bohemian brethren and the older community.