“What is hateful to you, do not do unto others. That is the whole Torah, the rest is commentary.” This is the most famous teaching of Hillel. What makes this teaching so extraordinary is that it was offered to a Gentile seeking an on-the-spot conversion. Teachings, stories, and legal rulings of Hillel can be found throughout the Talmud; what many of them share is his emphasis on ethical and moral living as an essential element in Jewish religious practice. After offering that concise summation of the Torah’s contents, Hillel adds the injunction to “now go and study,” and then converts the seeker to Judaism. For Joseph Telushkin, this is not a metaphor but a model. Faced with unprecedented levels of intermarriage and assimilation, and with the interest of so many unchurched non-Jews in Jewish teachings, Judaism today is in need of the sort of openness that Hillel championed 2,000 years ago. The most prominent religious leader in the Land of Israel during the reign of Herod, Hillel may well have influenced Jesus, his junior by several decades. In a provocative analysis of the evolution of both Christianity and Judaism, Telushkin reveals why, over the ensuing centuries, Hillel’s teachings began to be ignored in favor of the stricter and less inclusive teachings of his rabbinic adversary, Shammai. This bold new look at an iconic religious leader—the first to cite the ethical concept of tikkun olam (repairing the world) as a basis for making modifications to Jewish law—is certain to generate passionate discussion and debate.