Another significant cause furthering the spread of the Reformation in Poland was Polish religious tolerance. In the sixteenth century Poland was a country not only of political liberty, but also of intellectual freedom and of religious liberty. To be sure, owing to the pressure exerted by the clergy upon the kings, royal edicts, forbidding the dissemination of the new doctrines in the land and imposing severe penalties upon transgressors, were issued freely. However, these edicts violated constitutionally guaranteed liberties of the nobility, and, consequently, were never approved by any diet; hence, they had not the force of law, and remained largely a dead letter. As to the attitude of the kings themselves, they were rather tolerant of differences in religious belief and practice. Sigismund the Old, while a very good and loyal Catholic and a ruler who seemed to be easily induced to issue decrees proscribing the new religious movement, was very tolerant personally. When Johann Eck, the German Catholic theologian and zealous opponent of Luther, called on him to adopt a stern policy and to use severe measures in suppressing Lutheranism in Poland, the king replied that his desire was to rule over the goats as well as over the sheep.[253] When, again, in July, 1546, Pope Paul III urged him to take an active part on the side of the cause of the church in the religious war which had broken out in Germany at this time, Sigismund I not only refused to do so, but also by royal order forbade Polish citizens to engage even privately in any way on either side of the German controversy and conflict.[254] Then, too, it was Sigismund I who in 1525 consented to the secularization of the Teutonic Order and of the Duchy of East Prussia, then a part of the Polish kingdom. And it is a well known fact that his court was unusually liberal and a safe shelter for humanists and humanistic sympathizers with the Reformation movement.