The entire tree is the Church, being deification in the Angel of the Lord, the Angel now known as the Incarnate Christ. This does indeed go back to Paradise: the life of Adam and Eve is this same Orthodox Faith known in deification. "The Lord knows those who are His" (2 Tim 2:19).
would also like to emphasize that the incarnate Christ is not an angel. The angels are a distinct creation and are by definition non-corporeal, thus it is not possible for an angel to be incarnate and remain an angel - it would be a violation of his very nature. The Incarnate Christ is true God of true God and fully man as well - no mention of "angels" here. I realize that this reference may not have been Richard's intent - however, we have to be careful in how we speak of these awesome things so as not to be led astray.