  For his empirical premise Bonaventure turns again to truth, but ontological truth. All creatures are true to the extent that they actualize the potential perfections of their natures, and they are false to the extent that they fail to do so, because ontological truth is “the indivision of act and potency.” So “in a creature there is indivision combined with difference between act and potency.” All creatures are partial actualizations of truth. Ontological truth takes us to the heart of Bonaventurean metaphysics. Aristotle’s definition of prime matter as pure potency means that everything that contains potency of any sort, even an angel, must contain matter. This universal hylomorphism leads in turn to Bonaventure’s doctrine of being: “Matter gives independent existence (existere) to form, while form gives the act of being (essendi actum) to  matter.”[50]  Every created being (ens) is an ontological composite of independent existence (existere) and being (esse), where esse signifies the nature or essence of the thing. From rocks to angels, all creatures are true to the extent that the potencies of their “existence” given by matter are realized through the perfection of their “being” through form.