Laozi, the classical Chinese philosopher, was said to describe tea as "the froth of the liquid jade" and named it an indispensable ingredient to the elixir of life. Legend has it that master Lao was saddened by society's moral decay, and sensing that the end of the dynasty was near, he journeyed westward to the unsettled territories, never to be seen again. While passing along the nation's border, he encountered and was offered tea by a customs inspector named Yin Hsi. Yin Hsi encouraged him to compile his teachings into a single book so that future generations might benefit from his wisdom. This became known as the "Dao De Jing", a collection of Laozi's sayings.