A Zen student goes into a house, and places his walking stick at the
side of the front door.

The Zen master asks the student "Which side did you leave your stick:
on the right or on the left of the doorway?"

The student replies that he cannot recall: he has not yet achieved his
"every-minute Zen".

As I recall, this is from "Zen Flesh, Zen Bones" by Paul Reps.