Statement 1: It comes from the Zen saying that "it is natural to be cool when you are calm", and it will be cool when you are calm. Peace of mind is naturally cool, that is, peace of mind and natural cooling of the heart. Later, it was used to refer to dealing with problems in life with a calm mind when encountering problems, difficulties and setbacks. As the saying goes, "peace of mind is naturally cool", which shows that people's subjective feelings have a certain role. Statement 2: Yong Zhengdi in Qing Dynasty copied the instructions of Emperor Kangxi and edited them into Courtyard Mottoes. Among them, there is an instruction called "Peace of mind is naturally cool", to the effect that as long as you can achieve inner peace, it will not be hot. "People who don't open the window to enjoy the cool in summer are not hot because they are used to it since childhood and because they are calm." Even put forward, "and Xia Yue is not greedy for cold, which is also good for your health. If the moon in summer is full of yin, if you enjoy the comfort of cool air for a moment, you will turn off the heat in summer. I didn't feel hurt at that time, but I got sick later. Every time I see someone with an uncomfortable stomach in late autumn, it's because it's cold outside and hot inside. " Statement 3: The source is Bai Juyi's "Ku re Heng Ji Shi Chan Fang". The original text of this poem is: everyone is crazy in summer, and the only Zen master does not leave the room; It doesn't mean that there is no heating in the meditation room, and it is cool to be calm. Bai Juyi, a poet in the Tang Dynasty, visited the Zen master Henderson. It was very hot, but he found Master Hengji sitting quietly in the room. Bai Juyi asked:' Zen master! It's too hot in here! Why not change to a cool place? . Zen master Henderson said,' I think it's cool here! . So the poet Bai Juyi made this poem with an epiphany, and later generations summed up the truth that peace of mind is naturally cool from this poem.