 Other works produced by Hu 's studio included a reprint of Zhou <unk> 's manual of seal @-@ script calligraphy , The Six <unk> of <unk> , <unk> and <unk> ( <unk> <unk> <unk> , <unk> ) and the related <unk> Investigations into <unk> ( <unk> Bi Ji , <unk> ) , which discussed common errors in the formation of characters . With his brother <unk> , Hu edited a new introductory edition of the Confucian classics , entitled The <unk> Text of the Four Books , <unk> and <unk> ( <unk> <unk> <unk> , <unk> ) ( 1640 ) , giving the correct formation and pronunciation of the text . A similar approach was taken with the <unk> of the Thousand Character Classic in Six <unk> ( <unk> <unk> <unk> , <unk> ) ( 1663 ) , which Hu compiled with the aid of his calligraphy teacher , Li <unk> . It was published after Li 's death , partly in homage to him . 
