  Indeed, if Ibn Ezra can be located within any of the major philosophical traditions, his place is among the Pythagoreans. Sefer ha-Ehad is Ibn Ezra’s venture in arithmology. Like the writings of Nicomachus of Gerasa and Philo, as well as a relatively short list of medieval Muslim and Jewish authors, Sefer ha-Ehad follows the Pythagorean tradition of listing which natural, mathematical, and other items, come in two’s, three’s, etc. As we have seen in the preceding paragraph, Ibn Ezra pressed especially the theological implications of these arithmetic properties.