The creature needs life; the Spirit is the Giver of life. The creature requires teaching; it is the Spirit that teaches. The creature is sanctified; it is the Spirit that sanctifies. This chapter analyses the occurrence of doulology in early Christian pneumatology. Most ancient discussions about spirits inevitably centered on two issues, namely the spiritual taxonomy and the place and function of the spirit(s) in the cosmological hierarchy. The notion of the spirit/Spirit as a free companion or twin that guides the human soul/spirit was common in early Christian thought. The chapter expresses that the Trinitarian debates about the Holy Spirit, specifically those in Basil and Eunomius, need to be read within this same scheme of spiritual taxonomies and doulological classifications delineated above if one wishes to understand the role of slavery in this debate that was so formative of Christian thought in the centuries to follow.