[An excerpt from the preface of Red Pine:]

No one knows who P'u Ming was or when he wrote these verses

or whether he's also responsible for the accompanying woodblock

pictures. The earliest edition available to us was published by Chu

Hung in 1609. Despite being one of the most knowledgeable

monks of the sixteenth century, Chu Hung didn't know who P'u

Ming was either. The consensus among scholars is that he wasn't the

fourteenth-century monk of the same name noted for his paintings

of bamboos. In any case, P'u Ming's weren't the only oxherding

pictures around. And they certainly weren't the first. There were at

least three earlier sets of oxherding pictures by three Sung dynasty

(960-1279) monks; a series of five pictures by Ch'ing Chu, one of

six pictures by Tzu-te Hui and a set of ten pictures by K'uo An.

The pictures by Ch'ing Chu and Tzu-te Hui showed the ox

gradually becoming whiter until both it and the herdboy finally

disappeared in the fifth picture, which consisted of a circle. To this,

Tzu-te Hui added a sixth picture showing the boy returning to the

world, unattached. This was meant to point the viewer beyond the

emptiness that the circle seemed to imply. But this improvement

must have reminded P'u Ming of the man in the snake drawing

contest. Finishing his drawing before his competitors and not

knowing what to do, the man idly added feet to his snake and lost.

Hence, P'u Ming chose not to follow Tzu-te Hui's example. Instead,

he ended his series, as Ch'ing Chu had done, with the circle of

light. Also, by expanding Ch'ing Chu's earlier five pictures into ten,

he provided a commentary to one of the most popular Buddhist

concepts, the ten paramitas, or means to the other shore: charity,

morality, patience, devotion, meditation, wisdom, works, vows,

power and knowledge.

[...]

The origin of the oxherding metaphor can be traced to this

injunction delivered to the Assembly by the Buddha the night of his

Nirvana, "Monks, once you're able to keep the precepts, you should

prevent your five senses from indulging in the five desires. Be like

the herdboy with his staff in hand who watches over his ox and

keeps it from running through grain fields." (Testament Sutra)