Modern science is beginning to go back to old ideas about us, that we are holistic beings, and that all the different aspects of ourselves are related, and affect each other. But for a long while our society, and particularly perhaps medicine, has tried to understand people by dividing them up into different headings, and then looking at those different headings as though they were completely discrete from each other. The yogis knew, thousands of years ago, that we were extremely complex, and that all parts of us interrelate. Two models that they used show this particularly well: the model of the five maya-s (often called by the later name of the kosha-s), and the model of the chakra-s.