A commission. The story behind it:

One of the things that many zen monks accept as a restriction is that they are not allowed to touch women.

There are two monks walking by a swiftly flowing river. They encounter a woman who is on the other side of the river, but needs to get across very badly. She is unable to make it across by herself. The older monk immediately steps forward, makes his way across the river, helps the woman climb up onto his back, and carries her over the river. The two monks journey on.

The younger monk is shocked, offended, upset with the other monk. He goes on and on about how touching a woman has broken the rules he has agreed to live by. How could he do this? After many minutes and many footsteps have passed, the older monk turns to his companion and says, "I left the woman there by the river's edge. Why do you still carry her on your back?"