From "The Humanity of God" by Karl Barth.
In Jesus Christ there is no isolation of man from God or of God from man. Rather, in him we encounter the history, the dialogue, in which God and man meet together and are together, the reality of the covenant mutually contracted, preserved. and fulfilled by them. Jesus Christ is in his one person, as true God, man’s loyal partner, and as true man, God’s loyal partner. He is the Lord humbled for communion with man and likewise the servant exalted to communion with God. He is the Word spoken from the loftiest, most luminous transcendence and likewise the Word heard in the deepest, darkest immanence. He is both, without their being confused but also without their being divided; he is wholly the one and wholly the other. Thus in this oneness Jesus Christ is the mediator, the reconciler, between God and man. Thus he comes forward to man on behalf of God calling for and awakening faith, love, and hope, and to God on behalf of man, representing man, making satisfaction and interceding. Thus he attests and guarantees to man God’s free grace and at the same time attests and guarantees to God man’s free gratitude. Thus he establishes in his person the justice of God vis-a-vis man and also the justice of man before God. Thus he is in his person the covenant in its fullness, the kingdom of heaven which is at hand, in which God speaks and man hears, God gives and man receives, God commands and man obeys, God’s glory shines in the heights and thence into the depths, and peace on earth comes to pass among men in whom he is well pleased. Moreover, exactly in this way Jesus Christ, as this mediator and reconciler between God and man, is also the revealer of them both. We do not need to engage in a free-ranging investigation to seek out and construct who and what God truly is, and who and what man truly is, but only to read the truth about both where it resides, namely, in the fullness of their togetherness, their covenant which proclaims itself in Jesus Christ.