In Western Zen we could say that our family style is focused around social action. Many practice centers stress social action, or Engaged Buddhism, as part of spiritual practice, sometimes as the primary function. Because dualities are so deeply ingrained in us—we habitually see things in terms of this or that, self or other, right or wrong, good or bad—the practice of nonduality becomes an essential component of social action.
A commonly held, but incorrect, view is that meditators tend not to be very active in the world, that meditation can lead to a kind of quiet contentment. The truth is that Buddhists are dedicated to social action. Karuna, or compassion, is the function of wisdom in the world. This koan is addressing what practice, realization and actualization are all about.
The commentary to this koan says, "The point of testing students is to know them intimately as soon as they open their mouths." Testing students is a standard practice in Zen, a means of knowing them intimately. It's been going on for thousands of years in monasteries and it happens whether students are brand new or whether they've been around for a while. There are no exams to find out where people are in their practice, no personality profiles. The way to know is through seeing, feeling and so on. The testing is sometimes very casual: "How are you doing?" Sometimes very direct: "What is it?" Sometimes indirect: "How are your parents? What have you been doing for the last six months?" The question really is, how conditioned are you? How deeply has the practice affected your perception of yourself and the universe? In short, how do you combust your life?
Next in the commentary is, "An old master once said, 'Immeasurably great people are turned about in the stream of words.'" In our culture, words create a particular sticking point. Everything we do, everything we understand, is shaped and gauged by words and ideas. We need to go beyond the superficial meaning of words and see what's behind them in order to grasp what is really being communicated. "Guishan and Yangshan were so in accord in perfect teacher-disciple identification, that in Zen dialogues, it is often difficult to tell them apart." In the Zen literature, Guishan and Yangshan are held up as the model of perfect accord in the dharma. In reading their koans, it's hard to tell who's the master and who's the disciple, that's how close they were.