As in the previous two volumes, Balthasar’s concern is the revelation of God’s truth, or God’s revelation as truth. But if Jesus is the truth in person, God’s own authoritative self-interpretation, it is the Holy Spirit who exegetes this, the Son’s living exegesis of the Father. Hence the theme of the present volume, which is to contemplate the Spirit as “the indispensable guide who ‘leads’ us ‘into all truth’… according to Jesus’ promise that the Spirit ‘will not speak of himself, he will take what is mine and declare it to you.’ [When, therefore] he says ‘mine’ we must remember that all that the Father has also belongs to the Son. Here we discern the unity of the trinitarian work of salvation in the Church and in the cosmos, a work that is only the outward expression of the inner, personal wealth of God, indivisibly one and sole” (From the author’s Preface to the present volume).