This sentence was originally a health-preserving method of the ancients, but now it has become an old-fashioned advertising slogan for introducing some tonics.

The ancients said: "An immortal absorbs the aura of heaven and earth and collects the essence of the sun and the moon in order to live a long life." In fact, this sentence is well-founded. The so-called "aura of heaven and earth" refers to the weather (Air) and earth energy, the weather belongs to yang, and the earth air belongs to yin. The combination of weather and earth energy forms all things. "Suwen·Yin and Yang Yingxiang Dalun": "The weather leads to the lungs, and the earth energy leads to the lungs." "Follow the yin and yang energy to respect people's residences." "The place where a person lives is like swimming between the two qi. If there are favorable conditions and adverse conditions, he will live longer." From the above, we can see the beneficial effects of the two qi of heaven and earth on the human body. Then, in a blink of an eye, we look at our city - a world of steel and concrete, even the earth. They are all deprived of the right to breathe, so how can they get the energy to breathe? Not to mention the air, which has become poisonous. "Gathering the essence of the sun and the moon" simply means oxygen, the most basic element that maintains our lives, which is processed by the sun and the moon (I have learned it in physics class).