Kung-wu says that he was impelled to write a new commentary on Sun Tzŭ
because Ts’ao Kung’s on the one hand was too obscure and subtle, and
that of Tu Mu on the other too long-winded and diffuse. Ou-yang Hsiu,
writing in the middle of the 11th century, calls Ts’ao Kung, Tu Mu and
Ch’en Hao the three chief commentators on Sun Tzŭ, and observes that
Ch’en Hao is continually attacking Tu Mu’s shortcomings. His
commentary, though not lacking in merit, must rank below those of his
predecessors.