Ecclesiastical Hierarchy is a work by Pseudo-Dionysius the Areopagite. It covers the hierarchies within the church system and reflects on the liturgical rites of the Byzantine church.
First of all, you have to love this guy's name. Yes, I know that the "pseudo" just refers to misattribution of later Neoplatonic writing to one of the early church fathers, but I also love that a Christian religious leader is named after the Greek god of wine with the further reference to the Areopagus, which feels very pagan to me.
A lot of this work is obscurely written and filled with theological gobbledygook. Did he just pull this stuff out of the air? Or is it built on church traditions? Or his personal mystical experiences? Or what? Maybe it doesn't matter and maybe any sort of attempt to make much of it rational misses the point. I did get a sense in reading this of a deep mystical connection to the divinity. The process of cleansing and initiation accompanied by obscure formal rites that can open the way to God for the prepared seeker felt promising to me. For the person with the right frame of mind, elaborate ritual can have great meaning, even if it based on nothing more than a need to set the right mood for a person who is ready to receive it. I could see this as a path to spiritual enlightenment, a path that would be better for me than the self-inflicted suffering advocated by John of the Cross. And it is certainly more attractive as a religious path than the go-to-Sunday-School/sing-hymns/hear-the-sermon Protestant Christianity that I was brought up on.