Sometimes also written Daoism, Taoism is a philosophy which later also developed into a religion. Tao literally means "path" or "way", athough it more often used as a meta-physical term that describes the flow of the universe, or the force behind the natural order. The Three Jewels of the Tao are compassion, moderation, and humility. Taoist thought focuses on wu wei ("non-action"), spontaneity, humanism, relativism, emptiness and the strength of softness (or flexibility). Nature and ancestor spirits are common in popular Taoism, although typically there is also a pantheon of gods, often headed by the Jade Emperor. The most influential Taoist text is the "Tao Te Ching" (or "Daodejing") written around the 6th Century B.C. by Lao Tzu (or Laozi), and a secondary text is the 4th Century B.C. "Zhuangzi", named after its author. The Yin and Yang symbol is important in Taoist symbology (as in Confucianism), as are the Eight Trigrams, and a zigzag with seven stars which represents the Big Dipper star constellation