Meir ben Isaac Eisenstadt was an authority on halakha who was consulted by rabbis from Turkey, Germany and Italy. He served as dayan in Posen and rabbi in Szydłowiec, Poland before moving to Worms where he headed the yeshiva. When Worms was captured by the French in 1701 he moved to Prostějov (German: Prossnitz) as rabbi. He briefly returned to Szydłowiec before settling in Eisenstadt as rabbi of the Seven Communities. Eisenstadt greatly influenced the nature of the community and his yeshiva attracted students from far and near. His best known student is probably Jonathan Eybeschütz. His major works are; "Or ha-Ganuz", novellae on marriage law (Ketubot) and notes on Yoreh De'ah; "Panim Me'irot", responsa and novellae on various Talmudic treatises; "Kotnot Or", homiletic commentary on the Pentateuch and the Five Scrolls, (published, with the "Or Hadash" of his grandson, Eliezer Kalir, under the title "Meore Esh" the latter word being an abbreviation of "Eisenstadt").