The first volume of the official edition2 of Mao Tse-tung's Selected Works, published initially in October 1951, contained an essay 'On Practice'. The second volume, published initially in March 1952, contained an essay 'On Contradictions'. Both pieces deal specifically with philosophical problems ; and, according to introductory editorial notes, both were originally presented as lectures at the Anti-Japanese Military and Political College in Yenan in July and August 1937 respectively. The two pieces are note worthy because they are the only discussions of Communist philosophy that Mao included in his Selected Works. They are noteworthy also for other reasons. In contrast to many of Mao's lectures that were given prior to or during World War II and printed (and sometimes even reprinted) before they appeared in the official edition of Mao's Works, 'On Practice' and 'On Contradictions' do not seem to have been published until 1951 and 1952 respectively. And even in 1951-1952 the second of the two pieces was given rather unusual treatment. 'On Contradictions' much longer and much more important than 'On Practice'-was not originally published in the first edition of the Selected Works at the end of Volume I where it belongs chronologically, but at the end of Volume II. An editorial note in the first Chinese and Russian editions of Volume II acknowledged that it was out of place and declared that in later editions it would be found at the end of Volume I, where indeed it now is.3 Why was the publication of 'On Contradictions' in the Selected Works so long delayed? The just-cited editorial note is silent on this point. But a second editorial note to the essay declares that "on its inclusion in the present collection the author has made certain additions, abbreviations, and corrections".4 At first glance this statement seems superfluous, since a general announcement printed in Volume I and signed by the Editorial Board of the Central Committee of the Chinese Communist Party in