Zborowski, ardent advocates of the Reformation after 1550. Nor were the incomes of the clergy to escape the Polish nobility’s attack. Whenever the country was in financial straits, the nobility in a general diet assembled voted special taxes to meet special emergencies. The clergy, however, were not liable to these special taxes voted by the diets. They claimed exemption from them. Yet they did come forward in each emergency with a voluntary contribution, known as “subsidium charitativum.” This was based on a general estimate of the clergy’s general income. As this estimate usually constituted only one-third and frequently one-eighth of the real income of the clergy, their voluntary contributions based on such estimates were obviously far below their ability to pay. Manifestly this was unfair and unjust to the nobility. It, therefore, demanded that the clergy pay a contribution based on an evaluation of their specific sources of revenue, such as their estates, their tithes, and other sources of income.[426] To this demand of the nobility the clergy were most decidedly opposed. At the same time they were not a little apprehensive that it might result in consequences unfavorable to them. To safeguard themselves, they voted a liberal contribution of 40,000 florins in 1511 for the purpose of redemption of certain royal lands in Red Russia; and in exchange for this contribution they exacted from the king a solemn pledge that henceforth they would be free from military obligations and from all other burdens, with the exception of the customary subsidium charitativum, based on an evaluation of their general income, in cases of a pospolite ruszenie. A written document confirming the pledge of 1511 was issued to the clergy by the king, December 10, 1515.[427] This furnished the clergy a certain legal basis for their opposition to the nobility’s demands. When, therefore, the Diets of 1525 and 1527 imposed a tax on the specific sources of the clergy’s income, the clergy at their Synod of Łęczyce in 1527, owing to a threatening Tartar invasion, again voted a voluntary contribution to the country’s needs, but flatly refused to be taxed by the diets.[428]