Other works produced by Hu 's studio included a reprint of Zhou Boqi 's manual of seal @-@ script calligraphy , The Six Styles of Calligraphy , Correct and Erroneous ( Liushu Zheng 'e , 六書正譌 ) and the related Necessary Investigations into Calligraphy ( Shufa Bi Ji , 書法必稽 ) , which discussed common errors in the formation of characters . With his brother Zhengxin , Hu edited a new introductory edition of the Confucian classics , entitled The Standardised Text of the Four Books , Identified and Corrected ( Sishu Dingben Bianzheng , 四書定本辨正 ) ( 1640 ) , giving the correct formation and pronunciation of the text . A similar approach was taken with the Essentials of the Thousand Character Classic in Six Scripts ( Qianwen Liushu Tongyao , 千文六書統要 ) ( 1663 ) , which Hu compiled with the aid of his calligraphy teacher , Li Deng . It was published after Li 's death , partly in homage to him .