The I Ching is presented as an oracle. It is also the world’s oldest constantly used book. Up until the communist revolution, the book was as revered in China as the Bible was in the west. Tradition has it its principles originated with Fu Xi, the legendary ruler of China (2800 BC-2737 BC). It was said the 8 trigrams (the horizontal, solid and broken line symbols) were revealed to him supernaturally, as markings on the back of a turtle. By the time of Yu (2194 -2149 BC), the trigrams had been developed into a system of 64 hexagrams. King Wen of Zhou is said to have given each a description regarding its nature.
The I Ching philosophy influenced the literature and government of the Zhou Dynasty (1122 BC-256 BC). Confucius wrote commentaries on the I Ching called the "Ten Wings", as explanations of its deep meaning. The oracle was used exclusively by the ruling classes at this time and divinations were inscribed on turtle shells, as in the illustration above. In the 1970s, archaeologists discovered these records of readings, intact within Han dynasty tombs.
Rather than the work of one or more historical figures, the core of the divination text is now thought to be an accretion of Western Zhou concepts, dating to the end of the 2nd millennium BC. The main text is a set of oracular statements represented by the hexagrams. These are symbols each containing six horizontal lines. Each line is Yang (a solid line), or Yin (a broken line). Yin and Yang are proposed as the complimentary principles of the universe in balanced opposition, represented in a black and white circular symbol, commonly known in the west as yin & yang. This diagram of ultimate power is properly called Taijitu. It represents the concept of universal opposites in harmony.
Patterns similar to the taijitu also form part of Celtic, Etruscan and Roman iconography, where they too are loosely referred to as yin yang symbols, but no relationship between these and the original Chinese symbol has ever been established. This does not mean none exists, since from very early times, contact and trade between east and west occurred.
A small number of circular, mandala arrangements of hexagrams have been established over the ages. The bā gùa, the traditional arrangement of the trigrams, usually printed on a mirror, is also traditional and ancient. Yin and yang, whilst common expressions associated with many schools of classical Chinese culture, are especially associated with the Taoists. Another view holds the I Ching is primarily a Confucianist philosophical document. The fact both Confucianism and Taoism claim direct descent from it suggests it's the source of eastern philosophical thought.
In ancient China, the I Ching grew to have two distinct but interlinked functions, similar to magic and alchemy in the west. The first was as a compendium of ancient cosmic principles, the second was its use in divination. Due to these uses, it escaped the Royal court to be sold and told in marketplaces and on roadsides, serving the illiterate peasantry, while the educated elite used it to tune-up their virtue. The I Ching has influenced countless philosophers, artists and even business people throughout history.
Prior to the Tokugawa period (16031868 AD) in Japan, the I Ching was little known and used mostly for divination, until Buddhist monks spread its philosophical, cultural and political merits among the Samurai.
Early Chinese civilisation, in common with western alchemy, had various pre-scientific explanations for how nature comes together as a balanced system. The I Ching has been cited as an example of such a method where any observation could be interpreted, albeit enigmatically .
In his article "Explication de l'Arithmétique Binaire" (1703) Gottfried Leibniz writes that he has found in the hexagrams of the I Ching, a base for claiming the universality of the binary numeral system. The binary arrangement of hexagrams is associated with the Chinese scholar and philosopher Shao Yung (a neo-Confucian Taoist) in the 11th century A.D. He presented it both as a circle, and a rectangular block. Thus, he clearly understood the sequence represented a logical progression of values. However, while it is true the sequence represents the values 0 through 63 in binary notation, there’s no evidence he used it in computations.
Today the flag of South Korea is emblazoned with the taijitu and four of the eight I Ching trigrams representing Heaven, Water, Earth, and Fire (beginning top left, proceeding clockwise). The symbolism represents the alchemical origin of the universe.