the legend of the text ~ Lao Tzi was angered and frustrated with injustices and immorality of life in feudal China and decided to leave his home in the state of Zhou for a life in the wilderness.  When he reached the Western Pass (the border between the civilized China and the barbarian wilds), a guard petitioned him to record his teachings for the edification of future generations.  The elder sage complied, descended from his donkey and proceeded to write the entirety of the Dao De Jing in one sitting.  When finished, and without a backward glance, Laozi departed through the gate, never to be seen again.

Ying & Yang ~ 

The Ying & Yang are not exclusively a Daoist symbol but rather appear in much of Chinese thought to indicate the dark and the light * they are always portrayed as opposite and equal qualities * whenever one reaches a peak it naturally becomes the opposite quality * Ying and Yang are bound together as a mutual whole; you cannot have one without the other * the interaction of two things always gives rise to other things