Sun Tzu proved on the battlefield that his theories were effective (for example, at the Battle of Boju), that he had a successful military career, and that he wrote "The Art of War" based on his tested expertise. However, the "Zuozhuan", a historical text written centuries earlier than the "Shiji", provides a much more detailed account of the Battle of Boju, but does not mention Sun Tzu at all. Beginning around the 12th century, some scholars began to doubt the historical existence of Sun Tzu, primarily on the grounds that he is not mentioned in the historical classic "Zuo zhuan", which mentions
What Is Art? to justify their own tastes. Jahn notes the "often confusing use of categorisation" and the lack of definition of the key concept of emotion. Bayley writes that "the effectiveness of "What is Art?" lies not so much in its positive assertions as in its rejection of much that was taken for granted in the aesthetic theories of the time". Noyes criticises Tolstoy's dismissal of beauty, but states that, "despite its shortcomings", "What is Art?" "may be pronounced the most stimulating critical work of our time". Simmons mentions the "occasional brilliant passages" along with the "repetition, awkward language, and loose terminology".