Marital relationships....opting to choose the perfect brightest bulb in the box is no sin. But choosing to exchange a perfect bulb for a black light does nothing but keep the both of you in the dark, so always choose the brightest light emitting option.
Could incorporate this into a ceremony instead of a candle or sand. Have an empty box, have the officiant read this, and put something from our wedding day in that box. We can keep filling the box throughout the years with "treasures" we collect together.