There was once a jar of fresh, clean water. Every drop of water in the jar felt immensely proud of being so clear and pure. Day after day they would congratulate each other on how clean and beautiful they were. That was, until one day when one of the drops got bored with his ultra-clean existence. He wanted to try what it was like being a dirty drop. The other drops tried to talk him out of it, but he stuck to his guns. Hardly realising, when the drop came back all dirty he turned all the other drops in the jar into dirty drops too. They tried to get clean again, but couldn't. They tried everything to shake off the dirtiness. Finally, much later, someone dipped the jar in a fountain, and only when a lot of clean water entered the jar, did the drops regain their old transparency and purity. Now they all know that if they all want to be nice clean drops, then each and every one of them has to stay clean, even if they find it difficult. Putting right the mistake of one single drop entails a lot of work for everyone else. The same happens with us and our friends. If we want to live in a jar of clean water, each one of us will have to be a clean drop. None of us should try being the dirty drop who spoils everything. How about you? What are you? A clean drop? 
It's much harder to undo an unwise act than it is to act wisely right from the start. 