Although I read Church Dogmatics preparing to write my dissertation, this passage (CD IV/1, pp. 200 passim) did not stand out because it was not at the center of my interest at the time. It is now, and here by way of documentation is Barth explaining in his manner what I have also been attempting for years to say in mine.  I have in several places added italics for emphasis.

Is it a fact that in relation to Jesus Christ we can speak of an obedience of the one true God Himself in His proper being? . . . . We . . . have actually to affirm and understand as essential to the being of God the offensive fact that there is in God Himself an above and a below, a prius and a posterius, a superiority and a subordination. And our present concern is with what is apparently the most offensive fact of all, that there should take place within it obedience. . . . His divine unity consists in the fact that in Himself he is both One who is obeyed and Another who obeys.

There is another thing outside of God, the world created by Him as the totality of the reality willed and posited by Him and distinct from Him. In this totality as His elect creature there is another person, his worldly counterpart κατ’ ἐξοχήν [preeminently], man, who, according to Gen. 1.27, is in his twofoldness as man and woman the image of God, the image primarily of His co-existence as Creator with the creature . . . .  [Mythology confuses] the world and man with God, and carrying its own inner differentiation into the Godhead, speaking of the co-existence and reciprocity of a superior God in heaven and a subordinate goddess of earth.  No, not in unequal but equal, not in divided but in the one deity, God is both One and also Another, His own counterpart, co-existent with Himself.  We can say quite calmly: He exists as a first and as a second, above and below, a priori and a posteriori. . . .

We have to abandon [the idea that] there is necessarily something unworthy of God and incompatible with His being as God in supposing that there is in God a first and a second, an above and a below, since this includes a gradation, a degradation and an inferiority in God, which if conceded excludes the homoousia of the different modes of divine being. That all sounds very illuminating.  But is it not an all too human—and therefore not a genuinely human way of thinking?  For what is the measure by which it measures and judges?  Has there really to be something mean in God for Him to be the second, the below?  Does subordination in God necessarily involve an inferiority, and therefore a deprivation, a lack? Why not rather a particular being in the glory of the one equal Godhead, in whose inner order there is also, in fact, this dimension, the direction downwards which has its own dignity? Why should not our way of finding a lesser dignity and significance in what takes the second and subordinate place (the wife to her husband) need to be corrected in the light of the homoousia of the modes of divine being?

As we look at Jesus Christ we cannot avoid the astounding conclusion of a divine obedience. Therefore we have to draw the no less astounding deduction that in equal Godhead the one God is, in fact, the One and also Another, that He is indeed a First and a Second, One who rules and commands in majesty and One who obeys in humility. The one God is both the one and the other . . . .

There is no third way between belief in “obedience of the one true God Himself in His proper being” and the denial of it that so many theologians and biblical scholars are laboring to establish these days, presenting that denial as Nicene orthodoxy–a denial that now appears to be beyond question in many places, the neoorthodoxy of the Evangelical intelligentsia.  The outcome of their theology, carried down from their towers into “the world created by Him as the totality of the reality willed and posited by Him and distinct from Him” where he has a worldly counterpart, the “twofoldness as man and woman the image of God,” and all that flows from their being together, cannot help but be profound beyond imagination. They had better be right.