The excellent description of yin and yang actually begins in the fourth paragraph on this web page. The two opposing principles are explained, as well as how opposites interact with each other throughout the universe. (
http://www.wsu.edu:8080/~dee/CHPHIL/YINYANG.HTM
)
At this information-packed web site, you will find an answer based on the Sun, Earth, and stars. You will also learn about the I-Ching, the famous ancient Chinese book of philosophy and fortune-telling. (
http://www.chinesefortunecalendar.com/yinyang.htm
)
To learn more about the book this website supports, please visit its Information Center.