"Seated on his bed, a cup of lukewarm tea beside him, Frink got down his copy of the I Ching.  From their leather tube he took the forty-nine yarrow stalks.  He considered, until he had his thoughts properly controlled and his question worked out...He wrote  the question down on the tablet, then began whipping the yarrow stalks from hand to hand until he had the first line, the beginning.  An eight.  Half the sixty-four hexagrams eliminated already.  He divided the stalks and obtained the second line.  Soon, being so expert, he had all six lines; the hexagram lay before  him, and he did not need to identify it by the chart.  He could recognize it as Hexagram Fifteen.  Ch'ien.  Modesty.  Ah.  The low will be raised up, the high brought down, powerful families humbled;  he did not have to refer to the text-he knew it by heart.  A good omen.  The oracle was giving him favorable council."  The Man in the High Castle by Philip K. Dick.

This was my first introduction to a description of the I Ching and the idea of it interested me.  After that I heard references to "Tossing or Throwing the I Ching" but never really understood exactly what that meant or how one could divine a very specific question by reading yarrow straws. I didn't even know what exactly "Yarrow Straws" were.  Later while reading The Way of Zen by Alan Watts I understood what a Hexagram was and a little about the origins of the I Ching.

 A series of 6 Horizontal lines one above the other, some unbroken some broken.  Here is a picture of the South Korean Flag containing 4 Trigrams (there are a total of 8). These 4 are; Heaven,Water, Earth, and Fire. A combination of any two of the 8 Trigrams creates each of the 64 different Hexagrams.   A month ago as a birthday present for one of my sons I bought him a set of Yarrow Straws and the The I Ching or Book of Changes.  I used this as an opportunity to study it so I could teach my son how to use it if he so desired.