Judah ben Elijah Hadassi ha-Avel (“the Mourner,” fl. 1148–1149) was the outstanding Karaite of twelfth-century Byzantium. Although he lived in a Christian country and very likely did not know Arabic, his major opus, Sefer Eshkol ha-Kofer (The Cluster of Henna, Song of Songs 1:14) serves as a summa of Karaite Judaism as it had developed under Islam from the proto-Karaite ʿAnan ben David to the demise of the Jerusalem Karaite community in 1099. It provides an overview of Karaite law, polemics, theology, heresiology, and much more. As such, it is an invaluabl…