《易传·系辞传上·第十一章》
所以蓍草占筮用四十九根，其德性是圆通而神妙，六十四卦的德性是方正而有睿智，每卦皆有六爻，其意是很简易而贡献在我们面前的。
是故蓍之德圆而神，卦之德方以知，六爻之义易以贡。
So forty-nine stalks of milfoil are used for divination. Their virtue is complete and mysterious, and the virtues of the sixty-four hexagrams are square and wise. There are six lines in each hexagram, which are very easy and contribute to us.