The Jews of Poland were favored by two powers within the state, by royalty and in part by the big Shlakhta. They were opposed by two others, the clergy and the burghers. Aside from the interests of the exchequer, which was swelled by regular and irregular imposts upon the Jews, the kings derived personal benefits from their commercial activities. They valued the financial services of the Jewish tax-farmers, who paid large sums in advance for the lease of customs duties and state revenues or for the tenure of the royal domains. These contractors and tenants became, as a rule, financial agents of the kings, owing to their ability to advance large sums of money, and were incidentally in a position to exert their influence upon the court in the interest of their coreligionists. The high nobility in turn appreciated the usefulness of the Jewish farmers and tenants to their estates, which they themselves, with their aristocratic indifference and indolence, knew only how to mismanage. The protection which this class accorded the Jews, principally at the Diets controlled by them, was in exact proportion to the services rendered by the Jews as middlemen between them and the peasants. The magnates accordingly were entirely indifferent to the welfare of the rest of Jewry, the toiling masses of the Jewish population. Uncompromising hostility to the Jews marked the attitude of the urban estates, the merchants and artisans of the burgher class, with a considerable sprinkling of German settlers, whose influence was clearly noticeable. These organized tradesmen and handicraftsmen looked upon the Jews as their direct competitors. The magistracies, acting as the organs of municipal self-government, placed severe restrictions upon the Jews in the acquisition of real estate and in the pursuit of business and handicrafts, while the trade-unions occasionally set the riotous mobs at their heels. Still more resolute was the agitation of the Catholic clergy, which frequently succeeded in influencing legislation in the spirit of ecclesiastic intolerance. The interaction of all these forces shaped the legal and social status of the Polish-Lithuanian Jews in the course of the sixteenth and in the beginning of the seventeenth century, at a time when Poland was passing through the zenith of her political prosperity. The vacillations and upheavals in the position of the Jews were conditioned by the shifting of forces in the direction of the one or the other above-mentioned factors in the course of history. 2. THE LIBERAL RÉGIME OF SIGISMUND I.