What thoughts are you carrying?

Two monks were traveling by foot when they came to a river.  There was a prostitute there who asked the first monk to carry her across.  He was horrified at the prospect and refused.  The second monk knelt for her to get on his back and carried her across.  She thanked him and left.  A little later the first monk expressed his disapproval that the other had let that woman touch him. The second monk replied, "I put her down when we had crossed the river.  Why are you still carrying her?'