An Orthodox Misquoted St Augustine On the Holy Trinity § 47

He forgot to tell it was book 15 § 47 (§§ and chapters go through each book as independent numberings), but there is a § 47 in Book XV, and here is how it reads:

47. Are we therefore able to ask whether the Holy Spirit had already proceeded from the Father when the Son was born, or had not yet proceeded; and when He was born, proceeded from both, wherein there is no such thing as distinct times: just as we have been able to ask, in a case where we do find times, that the will proceeds from the human mind first, in order that that may be sought which, when found, may be called offspring; which offspring being already brought forth or born, that will is made perfect, resting in this end, so that what had been its desire when seeking, is its love when enjoying; which love now proceeds from both, i.e. from the mind that begets, and from the notion that is begotten, as if from parent and offspring? These things it is absolutely impossible to ask in this case, where nothing is begun in time, so as to be perfected in a time following. Wherefore let him who can understand the generation of the Son from the Father without time, understand also the procession of the Holy Spirit from both without time. And let him who can understand, in that which the Son says, « As the Father has life in Himself, so has He given to the Son to have life in Himself, » not that the Father gave life to the Son already existing without life, but that He so begot Him apart from time, that the life which the Father gave to the Son by begetting Him is co-eternal with the life of the Father who gave it: let him, I say, understand, that as the Father has in Himself that the Holy Spirit should proceed from Him, so has He given to the Son that the same Holy Spirit should proceed from Him, and be both apart from time: and that the Holy Spirit is so said to proceed from the Father as that it be understood that His proceeding also from the Son, is a property derived by the Son from the Father. For if the Son has of the Father whatever He has, then certainly He has of the Father, that the Holy Spirit proceeds also from Him. But let no one think of any times therein which imply a sooner and a later; because these things are not there at all. How, then, would it not be most absurd to call Him the Son of both: when, just as generation from the Father, without any changeableness of nature, gives to the Son essence, without beginning of time; so procession from both, without any changeableness of nature, gives to the Holy Spirit essence without beginning of time? For while we do not say that the Holy Spirit is begotten, yet we do not therefore dare to say that He is unbegotten, lest any one suspect in this word either two Fathers in that Trinity, or two who are not from another. For the Father alone is not from another, and therefore He alone is called unbegotten, not indeed in the Scriptures, but in the usage of disputants, who employ such language as they can on so great a subject. And the Son is born of the Father; and the Holy Spirit proceeds from the Father principally, the Father giving the procession without any interval of time, yet in common from both [Father and Son]. But He would be called the Son of the Father and of the Son, if— a thing abhorrent to the feeling of all sound minds— both had begotten Him. Therefore the Spirit of both is not begotten of both, but proceeds from both.

Source: Book XV (you'll have to scroll down) of On the Trinity

Note, Photius in Vivliothiki calls St Augustine (of whom he presumably read another book) "ho en tois hagiois Aougoustinos"./HGL