Instead of that he speaks of “economy,” a very important word in all ancient Christian theology. Today it is the method of producing the means of life; but economy is derived from oikos, meaning house; thus, building a house in this case, building God’s full life itself. God develops Himself eternally in Himself, and builds up His manifestation in periods of history. It is “economy,” building in a living and dynamic way the Trinity in historical manifestation. But this Trinity does not mean there are different essences; there is one Divine essence. If you translate “essence” by power of ‘being, then you have what these people meant.
There is one Divine power of being and each of the “economic” manifestations of the power of being participates in the full power of being. God has eternity, the ratio (reason), the logos in Himself. It is an inner word. And this is of course the characteristic of spiritual existence. If you say God is Spirit, you must also say He is trinitarian, namely He has the inner word within Himself, and has the unity with His self-objectivation. It proceeds from God, like the beam of the sun proceeds from the sun. This happens in the moment of creation. In this moment the Son becomes another one, a second person, and then a third person. But when Tertullian uses these words, we must not be misled by words, from the very beginning of our more difficult analyses which will inescapably come in the next weeks, concerning the Trinitarian and Christological problems. The words “substance” or “essence” mean power of being; the Divine power of being is in all of them. … And “persona” is not our “‘person”; “persons” are you and I; each of you is a person for himself. We are persons because we are able to reason, to decide, to be responsible, etc. This concept of person was neither applied to God this, not at all..,-nor was it applied even to the three hypostases in God, although the word “person” was applied not to God but to the Father, the Son and the Spirit. What did this word mean? Prosopon is “face,” “countenance,” or persona, the mask of the actor through which a special character is acted out. So we have three faces, three countenances, three characteristic expressions of the Divine, in the process of the Divine self-explication.
These are the classical formulas of a Trinitarian monotheism, which uses these formulas often, even in Tertullian probably, to cover philosophical implications with which he didn’t want to deal. But the Greeks wanted to deal with the implications they were philosophers and so they tried to interpret what the real meaning of these words is. But let me repeat: persona is never applied to God before the 19th century; He never was called person. Secondly, in all classical theology, the term persona is applied to the three faces, or countenances, or self-manifestations of God: God as abyss, or Father; God as form, or Logos; God as dynamics, or Spirit. But this immediately shows that persona in this sense does not mean the juristic or ethical personality which it means today, but it means the independent self- manifestation of God, the countenance, or if you want, the mask, but not mask in order to veil something, but to reveal something, namely a special character.