The tradition of philosophy in the Persian-speaking world is extraordinarily rich, creative and diverse. This anthology, which is divided into three volumes, aims to communicate something of that richness and diversity. The term "philosophy" is understood to in its widest sense to include theological debate, philosophical Sufism and philosophical hermeneutics (ta'wil). Extending over a period of more than two millennia, and showcasing translations by well-established scholars, the anthology offers full bibliographical references throughout. For anyone interested in exploring, in all their varied manifestations, the fascinating philosophical traditions of Persia, such a wide-ranging and ambitious work will be an indispensable resource. Volume 1 starts with the Zoroastrian period and extends to the time of Biruni and Oma Khayyam, paying special attention to the peripatetic school associated with Ibn Sina (Avicenna). During the pre-Islamic period philosophy was intertwined with religion, and it is within Persian religious texts such as the Gathas, the Denkard, and the Zoroastrian texts of the Bundahisn that philosophical discussions of subjects ranging from metaphysics to cosmology and eschatology are to be found.