Augustine: Earlier Writings (continued)
17. It is not surprising that we speak like this about an ineffable nature, for something similar is met with even in things which we see with our bodily eyes and judge with our bodily senses. When we are asked about a fountain we cannot call it a river, and when we are asked about a river we cannot call it a fountain; and if we take a drink from a fountain or a river we cannot call it either a fountain or a river. But we describe all these three things, together or severally, as water. If I ask whether what is in the fountain or in the river or in the tumbler is water, in each case the reply must be that it is; and yet we do not say that there are three waters but only one. Certainly we must take care that no one imagines that the ineffable substance of the Divine Majesty is like a visible corporeal fountain or river or tumbler of water. For the water which is now in the fountain does not remain there but flows out into the river; and when a drink is taken from a fountain or a river it does not remain in the place from which it is taken. Accordingly it can happen that the same water can belong successively to the fountain, the river and the drinking vessel. But in the Divine Trinity the Father cannot be now the Son and again the Holy Spirit. In a tree the root is simply the root, the trunk the trunk and the branches are nothing but branches. We do not use the word "root" of the trunk or the branches. Nor does the wood which belongs to the root pass in any way into the trunk or the branches, but remains only in the root. And yet the rule remains that the root is wood and the trunk and the branches are wood, but we cannot say there are three woods but one only. Possibly because of a difference in strength these portions of a tree may be so unlike that it would not be absurd to speak of three kinds of wood. At least all admit that if three goblets are filled from one fountain, we may speak of three goblets but not of three waters, but of water in the singular only. If you were asked about the goblets severally you would reply that there is water in each of them, although there is no passage from one to the other as we observed there was from the fountain into the river. These corporeal examples have been given not because they bear any real resemblance to the divine nature, but because they show the unity of visible things, and to let you understand that it is possible for three things not only severally but also together to be designated by a singular noun; so that no one may be surprised and think it absurd that we call the Father and the Son and the Holy Spirit God, but hold that in that Trinity there are not three Gods but One only, one substance.