Today, the 4th of tammuz, marks the Yahrtzeit of Yaakov Ben Meir Tam ZT”L, known as Rabbeinu Tam (1100-1171).

He was one of the primary authors of the Tosafos commentary on the Gemara. Grandson of Rashi. He was called “Tam” due to his wholesomeness and righteousness. Some of his responsa (questions and answers) are collected in Sefer Hayashar.

Also famous for the Rabbeinu Tam zman of 72.