The _Shulhan Arukh_ became the substructure for the further development of Polish rabbinism. Only very few scholars of consequence had the courage to challenge the authority of this generally acknowledged code of laws. One of these courageous men was the contemporary and correspondent of Isserles, Solomon Luria, known by the abbreviated name of ReSHaL[91] (ab. 1510-1573). Solomon Luria was a native of Posen, whither his grandfather had immigrated from Germany. Endowed with a subtle, analytic mind, Luria was a determined opponent of the new school dialectics (pilpul), taking for his model the old casuistic method of the Tosafists,[92] which consisted in a detailed criticism and an ingenious analysis of the Talmudic texts. In this spirit he began to compose his remarkable commentary on the Talmud (_Yam shel Shelomo_, "Sea of Solomon"[93]), but succeeded in interpreting only a few tractates. In all his investigations Luria manifested boldness of thought and independence of judgment, without sparing the authorities whenever he believed them to be in the wrong. Of the _Shulhan Arukh_ and its author Luria spoke slightingly, claiming that Joseph Caro had used his sources without the necessary discrimination, and had decided many moot points of law arbitrarily. In consequence of this independence of judgment, Solomon Luria had many enemies in the scholarly world, but he had, on the other hand, many enthusiastic admirers and devoted disciples. In the middle of the sixteenth century he occupied the post of rabbi in the city of Ostrog, in Volhynia. By his Talmudic lectures, which attracted students from the whole region, he made this city the intellectual center of Volhynian and Lithuanian Jewry. The last years of his life he spent in Lublin, where to this day there exists a synagogue which bears his name. Luria and Isserles were looked upon as the pillars of Polish rabbinism. Questions of Jewish ritual and law were submitted to them for decision, not only from various parts of their own country but also from Western Europe, from Italy, Germany, and Bohemia. Their replies to these inquiries, or "Responsa" (_Shaaloth u-Teshuboth_), have been gathered in special collections. These two rabbis also carried on a scientific correspondence with each other. As a result of their divergent character and trend of mind, heated discussions frequently took place between them. Thus Luria, in spite of all his sobriety of intellect, gravitated towards the Cabala, while Isserles, with all his rabbinic conservatism, devoted part of his leisure to philosophy. The two scholars rebuked each other for their respective "weaknesses." Luria maintained that the wisdom of the "uncircumcised Aristotle" could be of no benefit, while Isserles tried to prove that many views of the Cabala were not in accord with the ideas of the Talmud, and that mysticism was more dangerous to faith than a moderate philosophy.