Tai Chi gives birth to two instruments, two instruments give birth to four images, and four images give birth to gossip.

Yi zhuan copula upload: "It is easy to have Tai Chi, that is, two instruments give birth to four images, and four images give birth to eight diagrams." The specific expansion of the above figure 1 is the sequence diagram of Fuxi's sixty-four hexagrams in Figure 2 above. Both of these pictures are explaining and explaining the same thing: that is, from the perspective of sitting on the ground and looking at the sky, the law of seasonal changes caused by the ecliptic movement of the sun (the annual viewing movement of the sun).

The apparent motion of the sun on the celestial sphere can be divided into two situations, namely, Sunday apparent motion and annual apparent motion. "Sunday visual movement" is a phenomenon that the sun rises and sets every day, which is essentially a visual effect caused by the rotation of the earth. "Annual apparent motion" refers to the phenomenon that the earth's revolution causes the sun to "cross" between constellations.

Astronomy calls the annual apparent trajectory of the sun on the celestial sphere, that is, the great circle of the apparent path of the sun in the sky "ecliptic", that is, the projection of the orbital plane of the earth on the celestial sphere. The sun circles the celestial sphere once a year along the ecliptic.

The outer circle of figure 1 is the ecliptic, that is, the "one" of "Tao gives birth to one", that is, the "Tai Chi" shown in Figure 2.

However, when the ancients observed the apparent movement of the sun, they found that the movement of the sun changed from north to south. This process is just as described in the Tao Te Ching: "Everything is born naturally, isolated and independent, and it is not dangerous to walk. It can be the mother of the world. I don't know its name. The strong word cried, and the strong name was Da. It is in this process that yin and yang are produced due to the length of day and night and the change of temperature, which is divided into two, called "life two" and "one yin and one yang is called Tao". As shown in figure 2, "Tai Chi gives birth to two devices".

to be continued