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

Section 4.3: The Sacredness of "Number" — The Numbers of Great Elaboration and the Numbers of Heaven and Earth

The ancient understanding of "number" (数) fundamentally differs from later periods. In ancient thought, number was not an abstract mathematical concept, but the fundamental code of cosmic order.

The Xici Zhuan states:

"Heaven is one, Earth is two; Heaven is three, Earth is four; Heaven is five, Earth is six; Heaven is seven, Earth is eight; Heaven is nine, Earth is ten. The numbers of Heaven are five, the numbers of Earth are five; the five elements mutually attain their position and each has its combination. The numbers of Heaven are twenty-five; the numbers of Earth are thirty. The sum of the numbers of Heaven and Earth is fifty-five. This is how changes are completed and spirits and ghosts move." (天一，地二，天三，地四，天五，地六，天七，地八，天九，地十。天数五，地数五，五位相得而各有合。天数二十有五，地数三十，凡天地之数五十有五。此所以成变化而行鬼神也。)

This passage assigns the natural numbers one to ten to Heaven and Earth: odd numbers belong to Heaven (1, 3, 5, 7, 9), and even numbers belong to Earth (2, 4, 6, 8, 10). The sum of Heaven's numbers is 25, and the sum of Earth's numbers is 30. The total sum of Heaven and Earth's numbers is 55.

Why does a description of numbers appear here$35 Why does it say "This is how changes are completed and spirits and ghosts move" (此所以成变化而行鬼神也)—this is the fundamental reason for the changes and operations of all things under Heaven and Earth, and the movement of spirits and ghosts$36

Because in ancient thought, numbers are the skeleton of cosmic structure. The reason why all things under Heaven and Earth can operate, change, and flourish endlessly is that they follow the laws of numbers. One, two, three, four, five, six, seven, eight, nine, ten are not human-invented calculation tools, but the inherent order codes of Heaven and Earth.

The core operation of Shi divination—dividing the yarrow stalks, counting them, and returning the remainder—is essentially a mathematical calculation process. Each operation produces a number (6, 7, 8, 9), corresponding to old Yin, young Yang, young Yin, and old Yang. The combination of these numbers forms the hexagram—and the hexagram is a symbolic expression of the cosmic structure at a particular moment.

Therefore, Shi divination is not "gambling with random numbers to predict fate," but "revealing the cosmic structure at this moment through mathematical calculation." There is a world of difference between the two: the former is superstition, the latter is a simple, yet profound, "cosmology of numbers."

The Xici Zhuan further states:

"The Yi has four ways of the sage: In speech, the emphasis is on the words; in action, the emphasis is on change; in making artifacts, the emphasis is on images; in divination, the emphasis is on prognostication." (夫《易》，圣人之道四焉：以言者尚其辞，以动者尚其变，以制器者尚其象，以卜筮者尚其占。)

This passage explicitly lists the four functions of the Yi: 1. The Way of Speech (emphasis on words); 2. The Way of Action (emphasis on change); 3. The Way of Making Artifacts (emphasis on images); 4. The Way of Divination (emphasis on prognostication).

Please note: Divination is only the last of the four functions. It is placed alongside the teaching of speech, the guidance of action, and the creation of technology, not above them. This itself indicates that, in the understanding of the author of the Xici Zhuan, divination was not the core function of the Yi, but merely one of its many functions—even the last one.