Late in the Fifth Theological Oration, “On the Holy Spirit,” Gregory of Nazianzus notes two parallel developments that have occurred in the history of revelation. They proceed side by side, but in opposite directions: one moves from complexity to simplicity (vis-a-vis the worship of God), while the other moves from simplicity to complexity (vis-a-vis the knowledge of God).
First, on the turn from idols to the worship of the one God:
There have been in the whole period of the duration of the world two conspicuous changes of men’s lives, which are also called two Testaments, or, on account of the wide fame of the matter, two Earthquakes; the one from idols to the Law, the other from the Law to the Gospel. And we are taught in the Gospel of a third earthquake, namely, from this Earth to that which cannot be shaken or moved….And therefore like a Tutor or Physician He partly removes and partly condones ancestral habits, conceding some little of what tended to pleasure, just as medical men do with their patients, that their medicine may be taken, being artfully blended with what is nice. For it is no very easy matter to change from those habits which custom and use have made honourable. For instance, the first cut off the idol, but left the sacrifices; the second, while it destroyed the sacrifices did not forbid circumcision. Then, when once men had submitted to the curtailment, they also yielded that which had been conceded to them; in the first instance the sacrifices, in the second circumcision; and became instead of Gentiles, Jews, and instead of Jews, Christians, being beguiled into the Gospel by gradual changes. Paul is a proof of this; for having at one time administered circumcision, and submitted to legal purification, he advanced till he could say, and I, brethren, if I yet preach circumcision, why do I yet suffer persecution? His former conduct belonged to the temporary dispensation, his latter to maturity. (Oration 31.25)
One might not agree with his account of why the changes occurred as they did, but he is right to notice a gradual simplification in the worship of God, with fewer and fewer external necessities.
Second, Gregory notices that, in inverse correlation to this simplification, God Himself is gradually revealed in more and more depth and detail: 1
To this I may compare the case of Theology except that it proceeds the reverse way. For in the case by which I have illustrated it the change is made by successive subtractions; whereas here perfection is reached by additions. For the matter stands thus. The Old Testament proclaimed the Father openly, and the Son more obscurely. The New manifested the Son, and suggested the Deity of the Spirit. Now the Spirit Himself dwells among us, and supplies us with a clearer demonstration of Himself. For it was not safe, when the Godhead of the Father was not yet acknowledged, plainly to proclaim the Son; nor when that of the Son was not yet received to burden us further (if I may use so bold an expression) with the Holy Ghost; lest perhaps people might, like men loaded with food beyond their strength, and presenting eyes as yet too weak to bear it to the sun’s light, risk the loss even of that which was within the reach of their powers; but that by gradual additions, and, as David says, Goings up, and advances and progress from glory to glory, the Light of the Trinity might shine upon the more illuminated. For this reason it was, I think, that He gradually came to dwell in the Disciples, measuring Himself out to them according to their capacity to receive Him, at the beginning of the Gospel, after the Passion, after the Ascension, making perfect their powers, being breathed upon them, and appearing in fiery tongues. And indeed it is little by little that He is declared by Jesus, as you will learn for yourself if you will read more carefully. I will ask the Father, He says, and He will send you another Comforter, even the spirit of Truth. This He said that He might not seem to be a rival God, or to make His discourses to them by another authority. Again, He shall send Him, but it is in My Name. He leaves out the I will ask, but He keeps the Shall send, then again, I will send,—His own dignity. Then shall come, the authority of the Spirit. (Oration 31.26)
In sum, Gregory seems to see an inverse correspondence between elaboration of external ritual, on the one hand, and theological knowledge and understanding, on the other, such that, over time, the former must decrease and the latter must increase.