The Gateless Gate, by Ekai, called Mu-mon, tr. Nyogen Senzaki and Paul Reps , at sacred-texts.com
Goso said: "When you meet a Zen master on the road you cannot talk to him, you cannot face him with silence. What are you going to do?"
Mumon's comment: In such a case, if you can answer him intimately, your realization will be beautiful, but if you cannot, you should look about without seeing anything.