Why is Preface to Lanting called "Heart Seal of Jin and Tang Dynasties"

I don't need to introduce Preface to the Lanting Pavilion, as everyone in China knows it. The masterpiece of Wang Xizhi, a generation of book saints, is known as "the best running script in the world"! There are 17 "zhi" characters in the whole article, but none of them are the same! Its true version has been lost. It is said that Li Shimin, Emperor Taizong, loved the Preface to the Lanting Pavilion and put it in the mausoleum after his death. It has not yet been discovered, and it is the treasure of the country. The various versions of Preface to Lanting that we can see now are copies of ancient calligraphers. The Dragon Book copied by Feng Chengsu, a famous calligrapher in the Tang Dynasty, is the most famous and recognized best copy of Preface to Lanting, which is also called the Dragon Book because it was written in the "Dragon Year" of the Tang Dynasty. Wang Xizhi was from the Jin Dynasty, and the author was from the Tang Dynasty. He admired Wang Xizhi very much, so he named "Heart Seal of Jin and Tang Dynasties", which means that the talented people of Jin and Tang Dynasties were soul mates.