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