Do you have a ruler? Do you use it often? Most students have it in their pencil-case. Though I am a teacher, I have many rulers. They come in many colors and shapes. Some are bought by me at stationery store, some given for promotion at shopping mall. Some of them are cheap; some are not, even free!
Measuring is the major function of a ruler. With it, in our daily life, we learn how long or how wide of an object. There is an abstract ruler in our mind as well. It is our moral standard. It comes from inner heart through the way of feeling. I live by the moral standards that my parents set for me as a child. For example, not cheating, not hate, and being faithful. As time goes by, with my life experience, my moral standard is everyone should be free to do what makes them happy, as long as no one gets hurt.