Fuxi used “the bridge” in his fourth line to indicate that the reverberation of contact and consequent activity is flowing, even as the action out of mind is still. Ch’an monk P’u-hua said:
When they come in the light, I hit them in the light;
When they come in the dark, I hit them in the dark.
(“Dogen’s Manuals of Zen Meditation”, Carl Bielefeldt, pg 156, ©1988 Regents of the University of California)
P’u-hua was acknowledged to be an eccentric, and if he exaggerated his role in the activity out of stretch with sense contact, at least he conveyed his experience with clarity!
The founder of Soto Zen in Japan, Eihei Dogen, said:
When we let go of our minds and cast aside our views and understandings the Way will be actualized. One sage clarified True Mind (Reality) when he saw peach blossoms and another realized the Way when he heard the sound of tile hitting a bamboo. They attained the way through their bodies. Therefore, when we completely cast aside our thoughts and views and practice shikantaza, we will become intimate with the way… This is why I encourage you to practice zazen wholeheartedly.
(“Shobogenzo-zuimonki”, sayings recorded by Koun Ejo, translated by Shohaku Okumura, 2-26, pg 107-108, ©2004 Sotoshu Shumucho)
Kobun Chino Otogawa translated the components of the word “shikantaza” as follows:
Shikan means “pure”, “one”, “only for it”. Ta is a very strong word. It shows moving activity. When you hit, that movement is called ta, so “strike” is ta. Za is the same as in the word zazen, sitting.
(“Aspects of Sitting Meditation”, from the record of Kobun Otogawa’s talks on the Jikoji Zen Center website)
A very literal translation of shikantaza would be “pure hit sit”, although the word “hit” must be understood in the sense in which P’u-hua used it, as an expression of the the activity of the stretch already in existence as consciousness takes place.