In fact, half of the full text of Tao Te Ching is explaining the phenomenon of astronomical calendar, which is the same as the Book of Changes.
"Red" refers to the sun, and "Zi" refers to 24 o'clock in the evening when a child is a child, which can correspond to the meaning of the following scripture: the thick virtue is the thick son. Poisonous insects don't sting (stones), wild animals don't catch (jué) birds, and the bones are weak and the muscles are soft. Unknown animals and horses are well combined.
The ancients paid attention to sunrise and stayed at sunset. According to the law of Yin and Yang, it is the quietest time (around 12 o'clock at night), and everything is resting, so the poisonous insects are resting at this time, and the hunting of wild animals is over. Raptors also sleep in trees, so people are very relaxed after sleeping, so they are called weak bones and soft tendons, but even if someone wants to break their hands, it is not easy to do it halfway. A healthy man will be unconscious even if he doesn't think about men and women after sleeping.
Obviously, Lao Dan is describing natural phenomena and laws. One part of Tao Te Ching is about astronomical phenomena, and the other part is about human life phenomenon, that is, the calendar phenomenon based on astronomy. The first scientific action of mankind is to formulate a calendar to agree on the concept of time, and observing the movement of celestial bodies is the most direct and effective method. All the great classics in China are written in astronomical calendars rather than mysterious ones, but the conditions for recording at that time were very inconvenient (people have paper and pens today). Therefore, it is suggested to study classical Chinese, and then study the ancient astronomical calendar in particular.