Our source for this ancient teaching story is Zen Flesh, Zen Bones, a collection of lessons and other writings from Zen compiled by Paul Reps and published by Doubleday, which holds the copyright. It is a wonderful book.
Tanzan and Ekido were once traveling together down a muddy road. A heavy rain was falling.
Coming around a bend, they met a lovely girl in a silk kimono and sash, unable to cross the intersection.
“Come on, girl,” said Tanzan at once. Lifting her in his arms, he carried her over the road.
Ekido did not speak again until that night when they reached a lodging temple. Then he no longer could restrain himself. “We monks don’t go near females,” he told Tanzan, “especially not young and lovely ones. It is dangerous. Why did you do that?”
“I left the girl there,” said Tanzan. “Are you still carrying her?”