"The Exacting Master" number 50 of 200 from Robert Aitken's book Miniatures of a Zen Master.

Zhaozhou asked Nanquan, "What is the way?"

Nanquan replied, "Ordinary mind is the way."

Zhaozhou asked, "Does this way have a special character?"

Nanquan replied, "With the slightest intention it is lost."

Confused, Zhaozhou said, "Without intention or direction, how can one know what is the way?"

Nanquan replied, "The way is not subject to knowing or not knowing. Knowing is delusion while not knowing is mere blankness. When the way is truly attained, it is like a great emptiness, vast, expansive. So how can it be reduced to right or wrong?"

In this Zen story Nanquan (Nansen) is the the teacher and Zhaozhou (Joshu) is the student. It is from Zhaozhou, who later becomes a teacher, that we get the Gateless Gate of "Mu!"

Even when Zhaozhou penetrated this teaching, he still stayed and studied with Nanquan for and additional forty years before venturing out to teach. Both of these men were exacting in their practice. An example to us.

I sense that contained in this story is a question worth investigation.