Wang Xi-zhi is one of the most famous calligraphers during the Eastern Jin Dynasty of China. When he was very young, he practiced his art every day and never stopped.
Later he absorbed the strong points of all the other schools of calligraphy, and developed his own unique style of writing. Because of his achievements, he has been honored as one of China's sages of calligraphy.
One time, Wang Xi-zhi sketched in wood for an engraver to cut. Then the engraver found the ink had penetrated one centimeter into the wood.
"Ru Mu San Fen" is got from this story, which means the calligraphy is penetrating.
Now it is often used to describe expressing sharp ideas or profound views.
王羲之是中国东晋时代一个很有名的书法家，他从小就刻苦练字，从不间断。
以后又吸取了各个不同书法派的优点，形成他自己独特的个性。因为他在书法上的成就，人们都尊称他为中国书法界的“圣人”。
有一次，王羲之在木板上刻字，后来刻字的人发现墨汁渗入木板有三尺深。
“入木三分”就是从这个故事中得出来的，用来形容书法有力。
现在多用来比喻分析问题很深刻。