Rabbi Isaac was born in
Prague,
Bohemia in the 12th century. In his early years, he studied in
Regensburg under
Rabbeinu Tam and
Isaac ben Asher ha-Levi. In the following years, Rabbi Isaac served as the head of the city's
bet din. He was considered the most preeminent
rabbi of the city. He compiled
tosafot to most tractates of the
Talmud. A large number of his tosafot are on the tractate
Bava Batra, which are included in the first printed edition of the Talmud. He also known to have written tosafot on tractates
Pesaḥim,
Mo'ed Katan,
Bava Kamma,
Shabbat,
Ketubbot,
Gittin,
Sotah,
Nazir, and
Bava Meẓia. In his later life, Rabbi Isaac became embroiled in a controversy with
Eliezer ben Nathan of Mainz, who criticized several of Rabbi Isaac's statements and in his reply, Rabbi Isaac is said to have treated him with great respect. Among his pupils were
Ephraim ben Isaac of Regensburg. Due to similar appellation, he and
rabbi Isaac ben Meir are sometimes confused. == Notable Views ==