  To pursue this theme, Bonaventure made use of materials drawn from earlier philosophers about three important points: the transcendentals, the three Neoplatonic routes to God, and the difference between scientific principles and conclusions. About the transcendentals, Aristotle made metaphysics the science of substance. Centuries later, Avicenna transformed it into a science truly universal in scope by insisting that it study the nine accidents, as well as substance, and also the attributes that transcend the categories (Avicenna, Metaphysica, 1.5, 8). Philip the Chancellor codified this doctrine into four transcendentals—being, one, true, and good (Aertsen 1996, 25–70).  Bonaventure opens consideration of God in his Commentary on the Sentences by noting that the categorical attributes of being are “its special properties which characterize its imperfection,” but the transcendentals are “its general conditions which characterize its  perfection.”[42]  The transcendentals therefore set the terms for treating God.