This volume is a sound translation of the Fons vitae of Solomon ibn Gabirol (born 1021/1022), who was the first Jewish philosopher in Spain. In the Fons vitae, Gabirol argues that there is a sensible and an intelligible world; that everything in the sensible and intelligible world is composed of matter and form; that lower things are an example of higher ones by which they are caused; that the intelligible world is composed of universal intelligence, universal soul, nature, and universal spiritual matter; that the human soul possessed knowledge when it was made but lost it when it was joined to the body and must remember it through sense-experience; that it is good for the soul to turn away from sensible things and pour itself into intelligible ones so that it may realize its final cause of returning to the higher, intellectual world; and that the ultimate source of all being—the font of life—is something both one and good, something from which all being flows like water emanates from a spring or like light flows from the sun. These doctrines profoundly influenced medieval Christian thinkers. While Dominicus Gundissalinus (c. 1110 – after 1190), William of Auvergne (c. 1190 – 1249), and Thomas of York (c. 1220 – 1260) embraced key elements of Gabirol’s system, Albert the Great (c. 1200 – 1280) and Thomas Aquinas (1225 – 1274) sharply criticized Gabirol’s thought. Because of the Fons vitae, Gabirol is today widely recognized as one of the greatest Jewish Neoplatonists.