What is the subject of metaphysics? Throughout the centuries, two main lines of thought have emerged: one focusing on the concept of being as the adequate object of the human intellect; the other, focusing on the relation between the world and its transcendent cause. Berthold of Moosburg, often considered merely as an epitomizer of Medieval Platonism, is here shown in his deep, original engagement with the scopes and limitations of these two metaphysics, which he leads back, respectively, to Aristotle and Plato.