Cosmological Construction and Rational Essence of the Original Functions of the *Book of Changes* Based on Divination Tracing

Section 4.2: Yarrow Worship and Plant Spirit Power — Vestiges of Ancient Thought

Why does Shi divination use yarrow, and not other materials$33 This seemingly minor question hides a profound secret of ancient thought.

The Xici Zhuan states:

"Therefore, the virtue of yarrow is round and spiritual; the virtue of the hexagram is square and knowledgeable." (是故蓍之德圆而神，卦之德方以知。)

The virtue of yarrow is "round and spiritual" (圆而神)—harmonious and divinely responsive. The word "spiritual" (神) here is not superstitious; it reflects the ancient perception of the special properties of the yarrow plant. Yarrow (Achillea) grows slowly, is said to live for hundreds of years, and its stems are firm and hollow. These natural characteristics were endowed with cosmological significance in ancient thought: longevity symbolizes "lasting as long as Heaven and Earth," hollowness symbolizes "emptiness that can receive," and uprightness symbolizes "correctness without deviation."

But the deeper reason may be that the growth process of yarrow itself is a miniature cosmos of "change." From seed germination, to the unfolding of stems and leaves, to the blooming of flower clusters, to withering in autumn and winter, and regenerating in the following year—this cycle of life and death is precisely the natural symbol of the "Way of Change" described in the Zhouyi.

Choosing yarrow as a tool for Shi divination was not because it possessed some mysterious "divinatory spiritual power," but because its natural life itself embodied the "Way of Yi." Using yarrow in the Shi divination operation was to use a natural object that was in cosmic resonance with Heaven and Earth to simulate the laws of Heaven and Earth's operation—this is a profound way of thinking "observing the Way through things."

The Shuogua Zhuan (说卦传, Explaining the Trigrams) further reveals the essence of this ancient thought:

"In ancient times, when the sages made the Yi, they were mysteriously inspired by spirits and produced yarrow; they matched Heaven and Earth and relied on numbers; they observed changes in Yin and Yang and established the hexagrams; they elaborated on hardness and softness and produced the lines; they harmonized with the Way and regulated righteousness; they exhausted principles and fulfilled nature, reaching to destiny." (昔者圣人之作《易》也，幽赞于神明而生蓍，参天两地而倚数，观变于阴阳而立卦，发挥于刚柔而生爻，和顺于道德而理于义，穷理尽性以至于命。)

Please note the logical chain in this passage: "mysteriously inspired by spirits and produced yarrow" (幽赞于神明而生蓍) is the starting point, and "exhausted principles and fulfilled nature, reaching to destiny" (穷理尽性以至于命) is the endpoint. From yarrow, it ultimately leads to "exhausting principles and fulfilling nature, reaching to destiny"—thoroughly understanding the principles of all things, exhausting the truth of one's fundamental nature, and ultimately comprehending the profound mystery of destiny.

This is a complete epistemological program, not an operational manual for divination. "Exhausted principles and fulfilled nature, reaching to destiny"—is this a realm attainable by divination$34 This clearly points to the ultimate pursuit of philosophy, and even ontology.