The Emperor's Internal Medicine, "The End of Diagnostic Essentials" says: In the first and second months of the year, the weather starts to change, the earth's energy begins to rise, and the human's energy is in the liver. In March and April, the weather is positive and the earth’s atmosphere is positive.

To be precise, this calendar should be called the Chinese lunar calendar. The Chinese lunar calendar is currently the most scientific calendar in the world. Its essence is neither a pure lunar calendar nor a pure solar calendar, but a combined lunar and solar calendar. Simply put, the lunar calendar is a calendar that records the changes of the moon, and the solar calendar is a calendar that records the changes of the sun according to the earth's revolution cycle. The Chinese lunar calendar generally adopts the method of setting seven leaps every 19 years, which successfully takes into account the visual cycles of the sun and the moon. The law is therefore a luni-solar calendar. Currently, the only such calendar in the world that is formulated and implemented by official governments for a long time is the Chinese lunar calendar. The Chinese lunar calendar was shaped by the Taichu calendar of the Western Han Dynasty, which was derived from the Zhuanxu calendar used by the Qin Dynasty. The Chinese lunar calendar has been improved many times in later generations, mainly related to the setting of solar terms and the insertion of leap months, but the basic idea has not changed.

The first month of the lunar calendar is usually around the beginning of spring. The modern Beginning of Spring is the day when the sun reaches 315 degrees longitude. However, the moon phase changes in the monthly cycle of this day every year are inconsistent, so the interval between the first day of the first lunar month and the Beginning of Spring in each lunar year is different. Fixed.

Another: "The Yellow Emperor's Internal Classic" is a medical book, but due to the unique thinking characteristics of ancient Chinese medicine, it also records a large number of astronomical and phenological characteristics. In addition, individual chapters also involve some clinical topics. Summary of forensic psychology and insights into ancient Zhu Youshu. However, the question of "how did human beings come from, all human thoughts, etc." was not covered. In addition, the so-called "mystery of meridians" is just a misunderstanding of the world. The main author of this book is probably an ancient Chinese medical worker and enthusiast from the Later Zhou Dynasty to the Western Han Dynasty. A small number of works from the Sui and Tang Dynasties are also included. Finally, after understanding this book, it is as hard as a migrant worker, and it is true that I have no regrets in life.