In III, 2 of the Church Dogmatics, Barth develops the analogy of relations revealed in Jesus Christ to obtain between three levels or ‘planes’ of persons in relationship. These are (i) within the Triune God as the eternal relation between the Father and the Son; (ii) between God and man as the free election by God that man should be his covenant partner; (iii) between human persons as the basic form of humanity. The single factor which constitutes this analogy, the one thing which is similar in spite of all the great dissimilarity between God and man, the indestructible imago Dei, is the concept of personal relationship, the dyad, the I-Thou encounter. This theme of personal relationship is central not only in its location within the Church Dogmatics but perhaps throughout Barth's theology.