Shoyoroku - Case 31: Unmon's "Pillar" [1]

Unmon, instructing the assembly, said,
  "The old buddha and a pillar intersect each other. What number of
   activity is that?"
The assembly was silent. He said on their behalf,
  "Clouds gather over the South Mountain; rain falls on the North Mountain."

[1]: see case 83 Hekiganroku.