Two major themes run through these studies by Gad Freudenthal; science and philosophy in the medieval Hebrew tradition; and the repercussions of Greek theories of matter in the medieval Arabic and Hebrew scientific traditions. The opening essays offer a sociologically-informed picture of the acceptance or rejection of the sciences among medieval Jews in Southern France. This is followed by studies of individual figures - on Gersonides' thought; on Maimonides' and Gersonides' respective views of astrology; on al-Fârâbî's philosophy of geometry; and two notes (translated from Hebrew) on less well-known thinkers. The second part of the volume is thematic; a study identifying in Anaximander's theory of matter the fountainhead of a long-lasting scientific problématique is followed by five essays on its reverberations in the works of authors as different as Saadia Gaon, Avicenna, Averroes, Shem-Tov Ibn Falaqera and the author of the mystic Sefer ha-maskil. They all sought and gave accounts for the unity and persistence of the cosmos, in which metaphysics often complements physics, some echoing Stoic physics, a topic to which special attention is devoted.