Confucius (551-479 BCE) taught a moral wisdom that would become a predominant social force in China from the second century BCE until the mid twentieth century. Confucianism does not teach a central doctrine that a God or gods should be worshipped, but it does embrace a system of ritual and emphasizes humanistic virtues and values. Daoism is both a philosophy and a religion, seeking a life and a mind in harmony with nature. Yin and yang, the essential opposites, are seen as fundamental principles of the universe in many religious and philosophical discussions.