The origin of transcendental thought is not to be sought in Kant's philosophy but is a medieval achievement. This book provides for the first time a complete history of the doctrine of the transcendentals, from its beginning in the Summa de bono of Philip the Chancellor (ca. 1225) up to its most extensive systematic account in the Metaphysical Disputations of Francisco Suarez (1597). The book also shows the importance of the doctrine for the understanding of philosophy in the Middle Ages. Metaphysics is called First Philosophy, not because it deals with the first, divine being, but because it treats that which is first in a cognitive sense, the transcendental concepts of being, one, true and good.