You have probably seen a male mallard before. They are the most common puddle duck across America and probably the most commonly recognized duck. It is a dappling duck similar to the wigeon, and unlike the ring-necked duck it has a visible ring around its neck.
This particular one was not dappling for its dinner but instead was begging from people on a city park pond. The shine on the feathers is from the oil the duck uses to waterproof its feathers. You can tell how well it works by the droplets of water hanging on here and there, but never soaking in. It’s the same principle you go after when waxing a car. This trait is why we developed the saying, “like water off a duck’s back.”
This waterproofing is important for dappling ducks, because they use their buoyancy in the feeding process. They don’t exactly swim like diving ducks, they float instead. When they tip up and have their heads far underwater with their tails sticking straight up, they are still floating. But if they were to become soaked, or waterlogged, it would interfere with their feeding. They would also have trouble maintaining their body heat. This ability to repel water is crucial for their survival.
Christians need to have a similar trait. We reside in a world which can steal away the warmth of our spiritual fervor. It will permeate our lives and hearts and defeat us internally, if we allow it. In order to thrive in our current environment we must learn how to keep the bad stuff out, even though we are fairly well floating in it. Failing to guard ourselves from this world will allow us to become saturated in worldliness, and in this state we will be less effective for the kingdom of God.
Proverbs 4:23, quoted here from the HCSB, is one of my favorite verses to help us to understand this problem. “Guard your heart above all else, for it is the source of life.” The human heart becomes corrupted by the world if we are careless about it. Then the life which flows from it will not be the life of Christ intended for us to live.