Interpretation or illustration?

The finders of the vestigia trinitatis had no wish to postulate a second and different root of the doctrine of the Trinity side by side with revelation. Far less did they wish to represent this second root as the only true one or to deny the revelation of the trinitarian God. But their action is deeply overshadowed by the question whether this is not precisely what they did. We are plainly dealing with that non-obligatory, uncommissioned and dangerous possibility whenever theological language, as here, thinks it must not just be the interpretation of revelation but also its illustration. Interpretation means saying the same thing in other words. Illustration means saying the same thing in other words. Where the line is to be drawn between the two cannot be stated generally. But there is a line, for revelation will submit only to interpretation and not to illustration. If we illustrate it we set a second thing alongside it and focus our attention on this. We no longer trust revelation in respect of its self-evidential force. CD I.1, p344,345

Christ as the primary theme

I sense that paragraph 8 is where things start to heat up. Volume 1 is all about revelation. Barth makes this comment: "God reveals Himself as the Lord; in this statement we have summed up our understanding of the form and content of the biblical revelation." CD I.1,p314

And, further on the same page:

"Historically considered and stated the three questions answered in the Bible, that of revealer, revelation, and being revealed, do not have the same importance. The true theme of the biblical witness is the second of the concepts, God's action in His revelation, revelation in answer to the question what God does, and therefore the predicate in our statement. Within this theme the two other questions, materially no less important, are answered. Similarly the doctrine of the Trinity, when considered historically in its origin and development, is not equally interested in the Father, the Son and the Holy Ghost. Here too the theme is primarily the second person of the Trinity, God the Son, the deity of Christ."

"...the basic presupposition..."

"In a dogmatics of the Christian Church we cannot speak correctly of God's nature and attributes unless it is presupposed that our reference is to God the Father, the Son, and the Holy Spirit. But the fact that the doctrine of the Trinity is the basic presupposition of God too is no obstacle to regarding it already as also and precisely the interpretation of revelation as such. Not as an exhaustive interpretation; to give that we should have to speak not only of the God who reveals Himself but also of the way He does it and the man to whom He does it, and we should thus stand in need of further anticipations from the area of specific doctrines; there are certain parts of christology and pneumatology that we should have to consider. What we do in fact gather from the doctrine of the Trinity is who the God is who reveals Himself, and this is why we present the doctrine here as an interpretation of revelation. ... When we say, then, that the doctrine of the Trinity is the interpretation of revelation or that revelation is the basis of the doctrine of the Trinity, we find revelation itself attested in Holy Scripture in such a way that in relation to this witness our understanding of revelation, or of the God who reveals Himself, must be the doctrine of the Trinity." CD I.1, p312