The "taijitu" (; commonly known as the "yin and yang symbol" or simply the "yin yang") and the "Ba-gua" ("Eight Trigrams") have importance in Taoist symbolism. In this cosmology, the universe creates itself out of a primary chaos of material energy, organized into the cycles of Yin and Yang and formed into objects and lives. Yin is the receptive and Yang is the active principle, seen in all forms of change and difference such as the annual season cycles, the natural landscape, the formation of both men and women as characters, and sociopolitical history. While almost all Taoist organizations make use of it, its principles have influenced Confucian, Neo-Confucian or pan-Chinese theory. One can see this symbol as a decorative element on Taoist organization flags and logos, temple floors, or stitched into clerical robes. According to Song dynasty sources, it originated around the 10th century CE. Previously, a tiger and a dragon had symbolized yin and yang.