THE authority in the Ancient Church on the Holy Spirit would have to be St. Basil the Great. (But Ante-Nicene writings on the Holy Spirit will likely be sketchy.)
St Basil the Great wrote his treatise On the Holy Spirit during the closing phase of the Trinitarian controversies of the fourth century. The Arians had previously denied the full divinity of the Son and the debate then turned to the Holy Spirit. In this work, without explicitly calling the Spirit ‘God,’ St Basil demonstrates that He, like the Son, is of one and the same nature with the Father, and that equal honor and worship therefore are due Him. This classic exposition of Trinitarian doctrine eloquently sets forth the distinction yet perpetual communion and conjunction of the divine Persons. At the same time it deals with the nature of theological language and with the theological significance of the Church’s tradition of worship and proclamation. Its message, though specifically addressed to the fourth century, speaks to all ages.