Karma-Yoga has specially to deal with these three factors. By teaching what they are and how to employ them, it helps us to do our work better. Human society is a graded organization. We all know about morality, and we all know about duty, but at the same time we find that in different countries the significance of morality varies greatly. What is regarded as moral in one country may in another be considered perfectly immoral. For instance, in one country cousins may marry; in another, it is thought to be very immoral; in one, men may marry their sisters-in-law; in another, it is regarded as immoral; in one country people may marry only once; in another, many times; and so forth. Similarly, in all other departments of morality, we find the standard varies greatly — yet we have the idea that there must be a universal standard of morality.