"God becomes and is man. His condescension to us, His being as we are, is an event. It is actuality [(ist Ereignis, ist Wirklichkeit)]. It is the act of the One who is free and able to do this. It is the powerful execution of His eternal resolve. It is a triumphant and indisputable and irrevocable fact [(Geschehnis)]. But man, on the other hand, only wants to exalt himself, only wants to be as God. He can never do it. He does not have the freedom or power. He may determine on it for long enough, but nothing will ever come of it. He will always fall back on himself and still be man. It is not paradoxical or absurd that God becomes and is man. It does not contradict the concept of God. It fulfills it. It reveals the glory of God. But it is certainly paradoxical and absurd that man wants to be as God. It contradicts the concept of man. It destroys it. Man ceases to be a man when he wants this. It does not involve any alteration in God for Him to become a creature. Even as such He is still the Creator [(Gott verändert sich nicht, indem er Geschöpf wird; er bleibt ja auch als solches der Schöpfer)]. But it does require an alteration in man—and one that is not given to him—to become God [(Der Mensch aber müßte—und eben das ist ihm nicht gegeben—sich selbst verändern, um Gott zu werden)]. He cannot hope and he need not concern himself that this will finally be attained. For his own good it is provided that he cannot pass his own limits, try how he will. The only result of his attempts is the revelation of his impotence [(die Offenbarung seiner Ohnmacht)] to do so, and, because he ought not to do so, the revelation of his shame [(die Offenbarung seiner Schande)]."
Karl Barth, CD IV/1, 418-419, underscoring mine. =KD IV/1, 464-465. In KD, as reproduced in the Digital Karl Barth Library, there are these words in bold, though CD does not emphasize them in any way. In order to get them all in, I have modified Bromiley's translation ("only wants to exalt himself and to be as God") ever so slightly at just that one point.
Heiko Oberman later argued that, of the two phrases in my header, only the second, i.e. Infinitum capax finiti, is faithful to the theology of Calvin ("Extra dimension in the theology of Calvin," Journal of ecclesiastical history 21, no. 1 (January 1970): 61 (43-64); see, four years earlier, "Die 'Extra'-dimension in der Theologie Calvins," in Geist und Geschichte der Reformation: Festgabe Hanns Rückert zum 65 Geburtstag, 323-356 (Berlin: Walter de Gruyter, 1966)).