The Scorpion (author unknown)
A zen master was bathing in the river when he noticed a scorpion almost drowning.
He lifted out the scorpion and placed it on a nearby rock to dry. Just was he was withdrawing his hand the scorpion bit him.
The people sitting by the river observed this and they said to him ‘What have you achieved? You have saved him, only to get yourself bitten.’
The zen master replied ‘I did what I had to do according to my nature. The scorpion did what he had to do according to his. I can not change him just as he cannot change me.’