58. In every matter connected with theology, one's idea is formed according to one's understanding. This is true also regarding those things of which it is said that the understanding ought to be kept under obedience to faith. Such things especially are those which concern three persons according to the Creed of Athanasius. The idea which is formed of a thing is the understanding of it. If there is no understanding there is merely knowing, and they are but empty words which are considered. The idea becomes clear in the other life. As for the sort of ideas formed by man about the Trinity and about the union of the Divine and the Human in the Lord they are numerous and such as destroy rather than build up. I do not wish to enumerate them because for the most part they are utterly incongruous. And yet, thought concerning God being one, and that one the Lord, is the principal and fundamental thought of all in the doctrine of the Church. Without that no one can be saved.