After Lao-Tzu's Tao-te Ching, the second most famous Taoist text is the Chuang-Tzu. It is truly a Chinese classic--a text filled with rich allegories emphasizing the ever-changing-but-always-the-same nature of life. The author, according the Shih Chi, was named Chuang Chou and he lived Chou Dynasty as a contemporary of King Hui (369-319 BCE) of Wei and King Hsüan of Ch'i. It is commonly asserted by scholars that his thought was largely derived from Lao-Tzu. Still, the Chuang-Tzu is a striking and mixed collection. Some of the earliest chapters probably represent the original author's thought, but the later chapters probably were added during the Ch'in and early Han periods. D. C. Lau notes that two interesting developments that separate Chaung Chou's thought from Lao-Tzu's: his tendency toward moral relativism and his almost Descartean struggle with sensory perception.