In 1673 AD, Kangxi wrote the famous "Blessings of Longevity" to his grandmother, the Empress Dowager Xiaozhuang, to "wish blessings for longevity".
The character "福" written by Kangxi is different from the full and square character commonly used in the folk. The character is narrow and long, which is thin (pronounced "shou"). The folks call it "long thin blessing", that is, The blessing of longevity. As the saying goes, "If you are blessed, you will have longevity, and if you have longevity, you will be blessed." However, due to the huge difference in the shapes of the two characters "福" and "Shou", no calligrapher has been able to combine the characters "福" and "Shou" into one character since ancient times.
The right half of the character "福" happens to be the way the character "shou" is written in Wang Xizhi's "Lanting Preface", making it the only existing calligraphy work in which "福" and "shou" are written in the same character. The word "Fu" is known among the people as "longevity among blessings, and both happiness and longevity". Because it is stamped with the seal of "Treasure of Kangxi's Imperial Pen", it has become the only "福" in China and even the world that cannot be hung upside down.