it from ancient Greek and Hellenistic philosophy. Similar ideas can also be found in early Rabbinical literature. In the Middle Ages, the analogy became a prominent theme in the works of most Jewish philosophers. Rabbinical literature In the Avot de-Rabbi Nathan (compiled c. 700–900 CE), human parts are compared with parts belonging to the larger world: the hair is like a forest, the lungs like the wind, the loins like counselors, the stomach like a mill, etc. Middle Ages The microcosm–macrocosm analogy was a common theme among medieval Jewish philosophers, just as it was among the Arabic philosophers who were their peers. Especially influential with regard to the microcosm–macrocosm analogy were the Epistles of the Brethren of Purity, an encyclopedic work written in the 10th century by an anonymous group of Shi'ite philosophers. Having been brought to Islamic Spain at an early date by the hadith scholar and alchemist Maslama al-Qurṭubī (died 964), the Epistles were of central importance to Spanish Jewish philosophers such as Bahya ibn Paquda (c. 1050–1120), Judah Halevi (c. 1075–1141), Joseph ibn Tzaddik (died 1149), and Abraham ibn Ezra (c. 1090–1165). Nevertheless, the analogy was already in use by earlier Jewish philosophers. In his commentary on the Sefer Yetzirah ("Book of Creation"), Saadia Gaon (882/892–942) put forward a set of analogies between the cosmos, the Tabernacle, and the human being. Saadia was followed in this by a number of later authors, such as Bahya ibn Paquda, Judah Halevi, and Abraham ibn Ezra. Whereas the physiological application of the analogy in the Rabbinical work Avot de-Rabbi Nathan had still been relatively simple and crude, much more elaborate versions of this application were given by Bahya ibn Paquda and Joseph ibn Tzaddik (in his Sefer ha-Olam ha-Katan, "Book of the Microcosm"), both of whom compared human parts with the heavenly bodies and other parts of the cosmos at large. The analogy was linked to the ancient theme of "know thyself" (Greek: γνῶθι σεαυτόν, gnōthi seauton) by the physician and philosopher Isaac Israeli (c. 832–932), who suggested that by knowing oneself, a human being may gain knowledge of all things. This theme of self-knowledge returned in the works of Joseph ibn Tzaddik, who added that in this way humans may come to know God himself. The macrocosm was also associated with the divine by Judah Halevi, who saw God as the spirit, soul, mind, and life that animates the