When I was a child, I only heard of two types of tea: Da Wan tea and Bi Luo Chun. Later on, I got to know tea because I studied traditional Chinese medicine and discovered that tea is also a medicinal herb. For example, when it comes to brewing Chuanxiong tea, the "Compendium of Materia Medica" records: "The tea has a bitter and sweet taste. It enters the hands and feet to reduce yin, the Tai Yin Jue Yin Jing, and is specialized in clearing the heart, lungs, and intestines. Chamomile is used to treat headaches, and ginger water is stagnant. Drinking it after drinking alcohol can introduce the bladder and kidney meridians." However, tea is ultimately cold, and I have a weak spleen and stomach. I remember drinking Pu erh tea once, and halfway through, I went to the bathroom. Since then, I rarely drink tea, but a chance encounter changed my opinion. Not long ago, I went to explore Wudaoying Hutong next to Yonghe Temple in Beijing and arrived at a small shop. The shopkeeper is my good friend and invited me to drink Biluochun. This is a green tea. How could I drink it on an empty stomach when it was time for dinner? So I politely declined. But my friend said, if you taste it, you can guarantee that it won't be cold. She said that this tea originated from an 80 year old tea tree, harvested from the mountains of Dongting Lake, facing the sun. This is the first batch of pre Ming tea harvested from this tree, which has been manually picked, killed, and used firewood, and is not like other green teas. Unable to resist persuasion, I sat down and tasted this Bi Luo Chun. A few cups into my stomach, I was surprised to find that my stomach and intestines felt slightly warm and comfortable, without any signs of diarrhea. I let out a few moans and felt quite comfortable, and even had a feeling of fullness. I drank until 8 pm before leaving, drinking tea on an empty stomach without any discomfort, with a slight feeling of fullness and no hunger. Warm tea entered my stomach, and I sweated slightly, feeling very comfortable. Later on, my friend gave me some of this Biluochun, and I went back to drink it. The feeling was the same every time, it seemed to be no coincidence. This encounter changed my understanding of tea, especially green tea, and reminded me of an elderly man who once said that his father, who was over ninety years old, drank tea all his life, lived a long and healthy life, and the elderly were no exception. I initially thought it was due to my physical condition, but now it doesn't seem to be entirely true. After careful consideration recently, I suddenly realized something. Although tea has a cool nature, its ultimate warmth or coldness depends largely on two factors: the growing environment, whether it is in a cold, damp, or warm place, or whether it belongs to a sunny and warm environment. Just like the grapes in the north are different from those in Xinjiang, there is a traditional Chinese medicine called Achyranthes bidentata. Sichuan's Sichuan Achyranthes bidentata promotes blood circulation, while Henan's HuaiAchyranthes bidentata nourishes the liver and kidneys. For example, ginseng, produced in Northeast China, has a warm nature, while American ginseng tends to be cooler, both of which are from different regions. The essence of different production areas lies in different growth environments, including temperature, sunlight, soil, and planting methods. The second is the processing method, which may be more important. Most teas need to go through withering, and one step in withering is roasting with fire. Traditional Chinese medicine believes that traditional Chinese medicine and herbal medicine that have been processed by artillery often have different properties of coldness, heat, warmth, and coolness. For example, raw licorice has a cold nature and can clear heat and detoxify, while roasted licorice can invigorate the spleen and replenish qi; Raw Rehmannia glutinosa has a cool nature that cools the blood and promotes blood circulation, while Rehmannia glutinosa steamed by fire has a slightly warm nature that nourishes the kidneys. Most medicinal herbs that have been processed by fire will have some warmth, depending on the specific method of fire processing, and even the firewood and oven may not be the same. There are many processes involved in the processing of tea, many of which involve pyrometallurgical techniques such as baking or steaming. This tea making process determines the temperature of the tea. I used to think that fermented teas such as black tea and black tea were not cold because I didn't understand the fermentation process of tea. The fermentation of tea is usually carried out by spreading the tea leaves flat and letting them stand at room temperature of around 25 degrees Celsius, so it is different from fire fermentation. Therefore, in summary, the temperature of tea depends on the environment and the craftsmanship. It seems that people with cold constitutions are not necessarily unable to drink green tea, but some fermented teas, such as Pu erh tea, may not be suitable. Therefore, finding the right tea for oneself and understanding the principle of excess is not enough is the key to finding a way to maintain one's health. (New Press) (The author is the chief physician of the Department of Cardiology at Xiyuan Hospital, Chinese Academy of Traditional Chinese Medicine)