Rabbeinu Tam Jacob ben Meir (1100 in Ramerupt – 9 June 1171 (4 Tammuz) in Troyes), best known as Rabbeinu Tam (), was one of the most renowned Ashkenazi Jewish rabbis and leading French Tosafists, a leading halakhic authority in his generation, and a grandson of Rashi. Known as "Rabbeinu" (our teacher), he acquired the Hebrew suffix "Tam" meaning straightforward; it was originally used in the Book of Genesis to describe his biblical namesake, Jacob. Biography Jacob ben Meir was born in the French country village of Ramerupt, in the Aube département of northern-central France, to Meir ben Shmuel and Yocheved, daughter of Rashi. His primary teachers were his father and his brother, Shmuel ben Meir, known as Rashbam. His other brothers were Isaac, known as the Rivam, and Solomon the Grammarian. He married Miriam, the sister of R. Shimshon ben Yosef of Falaise, Calvados, who may have been his second wife. His reputation as a legal scholar spread far beyond France. Avraham ibn Daud, the Spanish chronicler of the sages, mentioned Rabbeinu Tam in his Sefer HaKabbalah, but not Rashi. The Italian Mishnaic exegete, Rabbi Isaac ben Melchizedek of Siponto, maintained a written correspondence with Rabbeinu Tam. Rabbeinu Tam's work is also cited by Rabbi Zerachya HaLevi, a Provençal critic. He maintained a scholarly correspondence with Aaron ben Joseph of Beaugency and received questions from students throughout France and from the Italian communities of Bari and Otranto. Rabbeinu Tam gave his Beth Din the title of "the generation's [most] significant court", and indeed, he is known for communal enactments improving Jewish family life, education, and women's status. At times, he criticised Halakhic opponents, notably in his controversies with Meshullam of Melun and Efraim of Regensburg. Halakhic disputes Legend has it that when Rashi was holding his infant grandson, the baby touched the tefillin that were on Rashi's head. Rashi predicted that this grandson would later disagree with him about the order of the scripts that are put in the head tefillin. Regardless of the episode's veracity, Rabbeinu Tam did disagree with the opinion of his antecedent. Today, both "Rashi tefillin" and "Rabbeinu Tam tefillin" are produced: the Shulchan Aruch requires wearing Rashi's version and recommends that God-fearing Jews wear both in order to satisfy both halakhic opinions. However: However, many Sephardic and chasidic Jews wear Rabbeinu Tam's Tefillin (in addition to wearing Rashi's) per opinions presented in the Shulchan Aruch and its extensive commentaries authored throughout the early-modern and modern era. The rise and articulation of chasidic philosophy has conflated the kabbalistic and halakhic aspects of Rabbeinu Tam's position, popularizing the custom to wear both pairs every day. Wearing Rabbeinu Tam tefillin is an almost universal custom among the many and diverse communities that follow the teachings of the Baal Shem Tov and his students. Another halakhic disagreement between Rabbeinu Tam and Rashi concerns the placement of the mezuzah. Rashi rules that it should be mounted on the doorpost in a vertical position; Rabbeinu Tam holds that it should be mounted horizontally. In a compromise solution, many Ashkenazi Jews place the mezuzah on the door in a slanted position. Sephardi Jews mount the mezuzah vertically, per the opinions of Rashi, Maimonides, and the Shulchan Aruch. Liturgical poet In the field of Hebrew poetry the importance of R. Tam is not slight. He was influenced by the poetry of the Spaniards, and is the chief representative of the transition period, in Christian lands, from the old "payyeṭanic" mode of expression to the more graceful forms of the Spanish school. According to Zunz, he composed the following pieces for the synagogue: