The fact that, according to the [first] Vatican Council, not only episcopalism but also papalism in the narrow sense should be regarded as a condemned doctrine is something that must no doubt be impressed in the public consciousness of the Christian world to a far greater extent than has hitherto been the case. In the great historical struggle of these two powerful movements, it puts itself neither on one side nor on the other, but creates a new position that goes beyond all human conceptualization in formulating the peculiar nature of the Church, which ultimately springs, not from man’s judgment, but from the word of God.
. . . Episcopacy and primacy, according to Catholic belief, are divinely given factors of the Church. Consequently, for the Catholic theologian there can be no question of playing one off against the other; he can only try to learn to understand more profoundly the living mutual relationship between the two and thus, of course, through his thinking, to serve its realization, which does indeed come about through men and is at all times a human and broken form of the given factor, of what God has given and given up for us in advance. K. Rahner has tried to explain this mutual relationship in more detail, on the basis of the concept of communion. That is, and doubtless remains, the central approach, inasmuch as the Church is, in her inmost nature, communio, a sharing of and fellowship in the body of the Lord. The reflection that the Church of the incarnate Word is in turn the Church of the word, and not just of the sacrament, leads us to a complementary aspect: sacrament and word are the two pillars upon which the Church stands — and we find in the relationship of these two elements, yet again, a polarity of unity-and-duality that cannot be further analyzed; this is the sign of something living that precedes and goes beyond any logical constructions and can never be entirely enclosed within them. Yet if in our investigations we start from the word, we are led to the concept of successio, which is affected, not . . . by the reality of communion, but by the struggle concerning the ‘word’; and it is there that it finds its proper place, even though it does in fact necessarily include the realm of communion as well. The problem of primacy and episcopacy is reflected in the concept of succession . . . .
From a 1961 essay, ‘Primacy, Episcopate, and Successio Apostolica’, by Joseph Ratzinger.