In his essay on Augustine in The Oxford Handbook of the Trinity , a precis of his Augustine and the Trinity , Lewis Ayres offers two lovely quotations illustrating Augustine’s pneumatology. He begins with one from the final book of The Trinity and follows with one from Augustine’s Tractates on the Gospel of John :

“Nor because [the Father and Son] give and he is given is he, therefore, less than they, for he is so given as the gift of God that he also gives himself as God. For it is impossible to say of Him that he is not master of his own power, of whom it was said, ‘the Spirit breathes where he will’ . . . there is no subordination of the Gift and no domination of the givers, but the concord between the gift and the givers.”

Then: “[if] many souls through love are one soul, and many hearts are one heart, what does the very foundation of love do in the Father and the Son? . . . If, therefore, ‘the love of God [which] has been poured forth in our hearts by the Holy Spirit who has been given to us’ makes many souls one soul and many hearts one heart, how much more does [the Spirit] make the Father and Son and the Holy Spirit one God, one light, one cause.”