Which one did Tian Ji learn first?

Look at human history first, and then look at the history of astronomy.

The subject of human body is the knowledge of Chinese medicine, including Huangdi Neijing, Treatise on Febrile Diseases, Synopsis of the Golden Chamber and so on. This is more closely related to us. Because it is related to the physical and mental health of each of us. Learning well can protect the health of yourself and your family, and you can see less doctors or even not.

The secret is about the knowledge of feng shui fortune telling. This is more difficult, if it is not a specialized practitioner, it is of little significance. Just as a hobby, don't take it too seriously.