Car's Windscreen and Dust

I drive to UTAR everyday. There are lot of construction going on nearby my uni and the air condition is really bad and getting worse. Everyday when I back to home, I will splash some water on my car's windscreen to clear the dust on it, just to make it looks nicer. However, every time when I go to uni, it gets dirty again. The process to get dirty is very easy, I am driving my car and whenever any moving vehicles moving in front of my car, my windscreen just get 'brown' in few seconds. When I look at my windscreen during jam, I found that actually this is quite similar with human nature. When a person wants to learn how to be good, it always takes a longer time to nurture the good characteristics but when comes to bad characteristics, we might doing it without we realizing it. This concept is exactly the same as to learn what is good, a thousand days are not enough: to learn what is evil, an hour is too long. In our daily lives, there are lot of evil stuff around us, all these negative stuff will affect us without we realizing it. So, whenever we have free time, take a break and have some conversation with our inner-self and reflect on ourselves, whether what we are doing are correct or wrong, and we will be better and better in the future.