I Ching is an ancient Chinese manual of divination based on eight symbolic trigrams and sixty-four hexagrams, interpreted in terms of the principles of yin and yang. It was included as one of the ‘five classics’ of Confucianism.  I Ching, also known as the Classic of Changes, Book of Changes, Zhouyi and Yijing, is one of the oldest of the Chinese classic texts. It contains a divination system comparable to Western geomancy or the West African Ifá system; in Western cultures and modern East Asia, it is still widely used for this purpose. Formalized by Fu Hsi, the eight trigrams are the basis of the sixty-four hexagrams, which are all the possible double combinations of the trigrams.

One of the earliest methods of using the I Ching was to heat a tortoise until its shell cracked and to interpret the cracks that appeared!
Traditionalists use yarrow sticks to cast the I Ching. This is hugely complicated and involves fifty stalks of yarrow, one of which is set aside, and manipulating the remaining forty-nine stalks in four stages of operation. These four operations are repeated three times to form a line, and as there are six lines, six operation sets are required for the whole process, a time-consuming method. Given the complexity of the yarrow method, it was inevitable that a simpler method of casting a hexagram would develop, and today the most common way of casting a hexagram, is to use coins – ‘the Heavenly Pennies’. Some people strike a balance between the ultra-traditionalism of the yarrow and the upstart coins, by using specially made I Ching stones, which are marked with either a Yin or a Yang symbol. Traditionalists need not worry. The means may vary; the interpretation remains the same, harking back across the millennia to Ancient China.