What's the use of earth books?

Earth calligraphy refers to practicing calligraphy on the ground with a ground calligraphy pen made of sponge dipped in water. This convenient and environmentally-friendly calligraphy form integrates physical exercise and sentiment cultivation, and more importantly, it promotes the popularization of calligraphy art and improves the calligraphy level of practitioners. That is, hand, leg, waist and brain interact, and poetry is related to calligraphy. Yan Liu, the author of many local books, can penetrate the charm in Yan's bones through the back of the stone. There are many cursive writers, such as Wang Xizhi's Preface to the Lanting Pavilion, Yan Zhenqing's Manuscript for Sacrificing a Nephew, and Su Dongpo's Red Cliff Fu, which have gathered several ancient running script masters from China. Of course, there are more self-created, adding Lian Bi to regular script is also charming.