Although Riba’s commentary is the earliest extant representative of the initial stage of the Tosafist enterprise, the true image of independent Tosafist dialectics was embodied in R. Jacob b. Meir (R. Tam, d. 1171). R. Tam, scholar and communal leader, was the towering figure of the emerging Tosafist dialectic movement. Few written remnants remain from R. Tam’s own compositions, yet his influence is strongly felt on every page of the Talmud. His teachings became primary foci of later generations, and his opinions were always necessarily considered in all later Tosafist commentaries.
Relying on his only known work, the Sefer ha-Yashar, we can surmise the nature of R. Tam’s compositions. Sefer ha-Yashar contains a commentary that boasts complete and utter independence. His strong personality and bold creativity are sensed in his detachment from earlier sources. R. Tam forged his own path through the vast Talmud, and his personality stands at the fore of independent Tosafist dialectics.
Aryeh Leibowitz, “The Emergence and Development of Tosafot on the Talmud”, Hakirah 15 (Summer 2013), 152.