"John tells us that all things came into being through the Son who is God the Word abiding with you, Father, from the beginning. Paul in his turn enumerates the things created in the Son, both visible and invisible, in heaven and on earth. And while he is specific about all that was created in and through Christ, of the Holy Spirit he considers it enough simply to say that he is your Spirit.Therefore I concur with those chosen men in thinking that just as it is not expedient for me to venture beyond my mental limitation and predicate anything of your only-begotten Son except that, as those witnesses have assured us, he was born of you, so it is not fitting for me to go beyond the power of human thought and the teaching of those same witnesses by declaring anything regarding the Holy Spirit other than that he is your Spirit. Rather than waste time in a fruitless war of words, I would prefer to spend it in the firm profession of an unhesitating faith.

"I beg you therefore, Father, to preserve in me that pure and reverent faith and to grant that to my last breath I may testify to my conviction. May I always hold fast to what I publicly professed in the creed when I was baptized in the name of the Father and of the Son and of the Holy Spirit. May I worship you, the Father of us all, and your Son together with you, and may I be counted worthy to receive your Holy Spirit who through your only Son proceeds from you. For me there is sufficient evidence for this faith in the words 'Father, all that I have is yours, and all that is yours is mine,' spoken by Jesus Christ my Lord who remains, in and from and with you, the God who is blessed for endless ages. Amen."   The Mystery of the Holy Spirit, by Hilary of Poitiers (315-367 AD)  (excerpt from ON THE TRINITY 12.55-57)