Karl Barth, in his Göttingen Dogmatics, takes from neo-Reformed Dutch theologian’s, Herman Bavinck’s notion of Deus dixit (‘God has spoken’), as a way to think about the way God has revealed Himself bound up in a radical doctrine of the Word of God. Many have probably heard of Barth’s threefold form of the Word of God; it is in the early years of his 
time at Göttingen that this line of thinking got started for him; particularly as he was pressed upon to teach a Reformed dogmatics within a Lutheran setting. The following showcases the way Barth articulated his understanding of a threefold form of the Word in his early German days as an honorary professor of Reformed theology:
‘Verbum domini manet in aeternum.’ It is no other in that it is now the first, now the second, now the third; and always, whenever it is one of the three, it is also, in some sense, the other two. The Word of God upon which dogmatics reflects is . . . one in three, three in one: revelation, Scripture, preaching . . . not to be confused, not to be separated. One Word of God, one authority, one truth, one power—and yet, not one but three addresses. Three addresses . . . and yet, not three Words of God, authorities, truths, and powers, but rather, one. The Scripture is not the revelation, but rather proceeds from the revelation. Preaching is neither revelation or Scripture, but rather proceeds from both. But Scripture is the Word of God no lass than revelation, preaching no less than Scripture. . .. no “prius” or “posterius” therefore; no “maius” or “minus”; the Word of God in the same glory, the first, the second, the third: ‘unitas in trinitate’ and ‘trinitas in unitate’.[1]
If the reader is familiar with the Latin (Western) doctrine of the filioque Barth’s development on the Word of God is immediately apparent. Barth’s appeal to an analogy of the Trinity is rather evident in the way he develops his thinking on the Word of God. Some might think there is an inherent subordination present within the Latin filioque; the Greek Orthodox church thinks so. Even so, Barth’s genius is to take the Latin dogma on the Trinity and use that pattern as the way he attempts to think God’s Word for us in and from the eternal Logos who is the Christ. It is his turn to Christ wherein he finally has a way to think a theological development from a genuinely Christ conditioned way; as is evident in his development of the threefold form of the Word of God. Once Christ becomes the center of Barth’s thinking, in concrete ways, his lights turn on in a way that begins to illumine his theological development for the rest of his life.
What the cash out is from all of this for me is to continue to see how a genuinely Christ concentrated theology looks; from the Word down, as it were. Christians need to have this type of grounding in order to genuinely think Christianly. As Christians our aim, as Paul asserts, is the perfection of Jesus Christ. As the evangelist and theologian, John, tells us of the Dominical teaching on the Holy Spirit: “These things I have spoken to you while abiding with you. But the Helper, the Holy Spirit, whom the Father will send in My name, He will teach you all things, and bring to your remembrance all that I said to you (Jn 14.25-6).” This is what Barth is picking up on in his theology of the Word; i.e., that any genuine Christian theology will avoid speculation, and instead listen to the concrete breath of the Holy Spirit as He points us to the verities that Christ has taught, and continues to teach us as the Word of God for us.
[1] Karl Barth, The Göttingen Dogmatics, 3 cited by Bruce L. McCormack, Karl Barth’s Critically Realistic Dialectical Theology: Its Genesis and Development 1909–1936 (Oxford: Oxford University Press, 1997), 339.