Meanwhile, at the center of the fourfold.

The center, so called because it centers, that is, mediates, is neither earth nor heaven, God nor man. The in-finity that is to be thought here is abysmally different from that which is merely without end, which, because of its uniformity, allows no growth. On the other hand, the "more tender relation" of earth and heaven, God and man, can become more in-finite.

P. 188

I'm going to hazard a guess that the German for that abysmally different in-finity had an ab-grund in it.  ¶ 11:34 PM