The Great Wall of China is the only man-made object that can be seen from outer space. It was built centuries ago to protect northern China from invasion; and it did so until 1644 when Manchu invaders bribed a gatekeeper to let them through one section. Then, once inside, they wrought havoc on the sleeping defenders and the nation that rested secure behind it. The real weakness turned out not to be the enemy on the outside but the enemy on the inside that let them in.
So it is in our lives. No matter how well we hedge our lives around and how secure we try to make ourselves, if the gatekeepers of our lives can’t be trusted, the rest will probably do us little good and we will become our worst enemies. And those gatekeepers are our conscience and our self control