Nangaku said, "It is like someone riding in a cart. If the cart is not moving, is beating the cart the right thing to do or is beating the ox the right thing to do?"
This question directly relates to our practice. In Zen Master Dōgen’s interpretation, the ox is the mind, that which can aspire to practice, while the cart is the physical state, the vehicle for practice. But what does "the cart is not moving" mean? What does "the cart is moving" mean?
Commenting on this, Dōgen asked, "If a river is running alongside a cart, or if a cart is moving alongside a lake, the water and the cart are in mutual relation. It is not possible to say that one element is moving and one element is not moving. Is it the water flowing or is the cart moving? Does the moving of the cart mean that the water is not flowing?" Water can be taken to represents what is going on spiritually within the practice. Our practice and what is going on within our practice are in mutual relation. Can the cart of our practice be distinguished from the flowing of enlightenment?
Further, time is a series of instantaneous moments. In each instant, there is no movement, but the progression from instant to instant is continuous movement. Thus Dōgen says, "When we investigate the saying 'the cart is not moving,' we find that there is both 'not moving,' and no 'not moving,' because the cart must be in time. We could say, then, that flowing is the water’s not moving. It could even be said that the water’s moving is beyond ‘flowing'. Nangaku’s words, 'the cart is not moving,' go beyond a one-sided assertion that some thing is not moving."
So is beating the cart the right thing to do or should we be beating the ox? Can there be both a beating of the cart and a beating of the ox? Are beating the cart and beating the ox equivalent, or are they not?
Dōgen noted, "There is no method for beating a cart in the secular world." A method for beating the cart means a method such as zazen for regulating the physical state. "Although the common man does not have a method for beating the cart, there is a Buddhist method: it is the very eyes of learning in practice."
Even though we learn methods for beating the cart, they will not be appropriate for beating the ox. A method of beating the ox means a method for motivating the mind; for example, the seeking of rewards. Dōgen continues, "Though methods for beating an ox are common enough in the everyday world, we should investigate further and learn through practice the Buddhist way of beating the ox."
Zen Master Enchi Dai-an once said, "I have lived on Isan mountain for thirty years, eating Isan meals, shitting Isan shit, but not studying Isan Zen. I just watched over a castrated water buffalo." Is the ox we are beating a castrated water buffalo?
Or is it an iron ox? Zen Master Fuketsu Ensho once said, "The mind-seal of the ancestral masters is like the stuff of a molded iron ox."
Or is it an ox coated with mud? Zen Master Ryuzan once said, "I once saw two oxen coated with mud. They fought and entered the sea. There has been no news of them since."
Dōgen: "Should a whip do the beating or should the whole universe do the beating? Should the whole mind do the beating? Should the marrow be beaten flat? Should a fist do the beating?"
"There should be fist beating fist, and there should be ox beating ox." The ox exists as it is.
(adapted from Shobogenzo Zazenshin by Zen Master Dogen, 1242)