This document provides historical context about elements of the liturgy including the blessing, prokeimenon, and roles of clergy members. It discusses how the blessing of "Peace be with all" can be traced back to early Christian greetings. It also explains that the prokeimenon, meaning "placed before", involves singing a short verse or two of psalms before scriptural readings and has origins in the singing of Psalms of David between biblical passages. Additionally, it outlines the development of liturgical roles like the bishop representing God's throne and presbyters representing the apostles.