Old Zen story

Two Zen priests were on a journey. As the two approach a stream, there is a young woman waiting. The old priest picks up the girl and carries her across. The young priest is amazed for the old priest touched the woman, a practice looked down upon by monks.
The two continued along their way. Some miles down the path, the young priest beside himself in his righteousness, shouts at the old priest:
– How could you have touch that woman!
The old priest, leading the way, turns and replies:
– I left her at the stream miles away, why is it you still carry her?”