Extracts from the Wilhelm\'s I-Ching translation\'s introductory : « The Book of Changes – I Ching in Chinese – is unquestionably one of the most important books in the world\'s literature. Its origin goes back to mythical antiquity, and it has occupied the attention of the most eminent scholars of China down to the present day [i. e. around 1920]. Nearly all that is greatest and most significant in the three thousand years of Chinese cultural history has either taken its inspiration from this book, or has exerted an influence on the interpretation of its text. Therefore it may safely be said that the seasoned wisdom of thousands of years has gone into the making of the I Ching. Small wonder then that both of the two branches of Chinese philosophy, Confucianism and Taoism, have their common roots here. [...] »

« In the course of time, owing to the great repute for wisdom attaching to the Book of Changes, a large body of occult doctrines extraneous to it – some of them possibly not even Chinese in origin – have come to be connected with its teachings. The Ch\'in and Han dynasties saw the beginning of a formalistic natural philosophy that sought to embrace the entire world of thought in a system of number symbols. Combining a rigorously consistent, dualistic yin-yang doctrine with the doctrine of the \"five stages of change\" taken from the Book of History, it forced Chinese philosophical thinking more and more into a rigid formalization. Thus increasingly hairsplitting cabalistic speculations came to envelop the Book of Changes in a cloud of mystery, and by forcing everything of the past and of the future into this system of numbers, created for the I Ching the reputation of being a book of unfathomable profundity. [...] »

« At the outset, the Book of Changes was a collection of linear signs to be used as oracles. In antiquity, oracles were everywhere in use; the oldest among them confined themselves to the answers yes and no. This type of oracular pronouncement is likewise the basis of the Book of Changes. “Yes” was indicated by a simple unbroken line , and “No” by a broken line . However, the need for greater differentiation seems to have been felt at an early date, and the single lines were combined in pairs. To each of these combinations a third line was then added. In this way the eight trigrams came into being. »