Who used a jar of water to practice writing brush in ancient times?

Wang Xianzhi.

Wang Xianzhi's father, Wang Xizhi, is an outstanding calligrapher. Influenced by his father, Wang Xianzhi loves calligraphy. When he saw that his father's handwriting was very good, all the people were copying his handwriting, which really made him envious. I don't know when I can become a respected calligrapher like my father. Once, he couldn't help it and asked his father, "Father, why do you write so well?" Wang Xizhi smiled and said, "If you want to know the secret, come to the yard tomorrow morning." The next day, Wang Xianzhi came to the yard early and found that his father had already practiced calligraphy there. When Wang Xizhi saw his son coming, he pointed to the eighteen jars of water in the yard and said, "There is no secret to calligraphy. As long as you finish writing these eighteen jars of water, the words will naturally be written." Deeply inspired, Wang Xianzhi practiced calligraphy day and night. In a blink of an eye, year after year, when he finished writing the eighteen jars of water, everything comes to him who waits, and he finally became a great calligrapher.