The system of holy degrees is taken from Neoplatonism, where it was first fully developed, after Aristotle and Plato (Symposium). The man who is most important is Proclus, a Neoplatonic philosopher who has often been compared with Hegel; he has the same kind of triadic thinking, thesis, antithesis, and synthesis, arid brings all reality into such a system of holy degrees.
The surprising thing about Dionysius is that this system, which was the end of the Greek world, the summary of everything Greek wisdom had to say about life, was introduced into and used by Christianity. Shortly before, this system was used by Julian the Apostate in order to fight Christianity, in order to bring paganism in again in a large system, which is the basis for all Greek thinking, and for the new religion of he educated to which he wanted to introduce Christlanity. So Julian and the Christian theologians who were figbting with each other in a life and death struggle, now were united in a Greek Christian mystic and theologians, Pseudo- Dionysius, Dionysius created Christian mysticism by using the system of degrees.
This is what “hierarchy” means. The other book is “On the Divine Names.” The term “Divine names” is also a Neoplatonic term, which was necessary for the Neoplatonists when they brought all the gods of the pagans into their system, How could they do this? Because they followed the philosophical criticism of hundreds of years, and no educated Greek of that time believed literally in the pagan gods. But there was still the tradition, there was the popular religion, and so something had to be done about these Divine names, What they tried to show was that the qualities of the Divine were expressed in these names. These names cannot be taken literally, They express different degrees and powers in the Divine ground and Divine emanation; they point to principles of power, of love, of energy, and other virtues, but they are not something which in terms of “name” could be understood as special beings. This meant they discovered, in present-day terminology, the symbolic character of all our speaking about God. The writings about the Divine names can be found in all the Middle Ages; all theologians did this; they spoke about the symbolic meaning of everything we say about God, They didn’t use the word “symbol” at that time, but used the word “name,” i. e., expressing a character or quality. And when you today have a popular discussion or a bull session, and someone tells you,'” Now what we say about God is only “symbolic,” you can say that this “only” is very wrong, and as long as a real thinking theology exists, people have understood the symbolic character of what we say about God, and the wrong is on our side that we haven’t followed in this respect the insight of classical theology – of the Greek and of the Western church – but that we have fallen into a literalism against which all the Reformers, especially Calvin, were fighting. The symbolic interpretation of everything we say about God corresponds to the idea of God Dionysius develops. First of all, how can we know about Him? He answers: There are two ways of recognizing Him, the affirmative theology: all names, as far as they are positive, must be attributed to God because He is the Ground of everything; so He is designated by everything, everything points to Him, This is the positive theology, and this has to be done. God must be named with all names, But then, at the same time – there is a negative theology which denies that He can be named by anything whatsoever.