Obviously the king was unaware of the trap into which he had fallen, and he decreed that the rich man deserved to die and must make fourfold restitution for the sheep. It was a very severe view, and entirely just. But his own sin was not yet before his eyes; what he had done was still behind his back. He did not yet admit his own iniquity and hence would not remit another’s. But the prophet had been sent to him for this purpose. He brought the sin out from behind David’s back and held it before his eyes, so that he might see that the severe sentence had been passed on himself. To cut away diseased tissue in David’s heart and heal the wound there, Nathan used David’s tongue as a knife—St Augustine