Zeraḥ ben Natan (Troki, Lithuania, 1586–1640) was a Karaite scholar with profound interest in Jewish philosophy, Kabbalah, and Karaite philosophy. He lived most of his life in Troki, although his family was originally from Birże (Lith.: Biržai) in northern Lithuania. As a young boy, he was tutored by the famed Karaite scholar Yitṣḥaḳ ben Abraham: decades later Zeraḥ would write to the famous Jewish printer Menasheh ben Yisra’el (1604–1657) in Amsterdam requesting him to print Yitṣḥaḳ ben Abraham’s polemic against Christianity, Ḥizzuḳ Emuna. In the headings of his poems, Zeraḥ is referred to as a ḥakham; he probably conducted some administrative and religious duties in the Karaite community of Troki. Most of his life, however, he was dedicated to an endless quest for knowledge. He collected an impressive library with both printed works and manuscripts. In 1618, he travelled to Istanbul, where he studied Kabbalah and secular sciences with the Turkish Karaites for two years. Back in Troki by the early 1620s, he began to correspond with the rabbinic scholar and polymath, Yosef Shelomo Delmedigo (Crete, 1591‒1655), who at the time was employed by the Prince Krzysztof Radziwiłł II (1585–1640) in Vilna. Zeraḥ poses intricate questions on mathematics, astronomy, medicine, Kabbalah, and theology in his letters, and these questions are published in Delmedigo’s highly influential scientific opus Sefer Elim (“The Book of Elim”, Amsterdam, 1629). Thus, Zeraḥ has become part of the early modern history of science among the European Jews. In addition to many extant poems both in Hebrew and in the Karaim language, he wrote a treatise on the medieval philosophical classic, Guide for the Perplexed by Moses Maimonides (1135–1204), and a Kabbalistic commentary on the Song of Songs. Zeraḥ died in 1657/8 at the age of seventy-nine.