The "Two Theories" refer to two works by Mao Zedong, "On Contradiction" (Maodun lun, 矛盾论, 1937) and "On Practice" (Shilian lun, 实践论, 1937). "On Practice" and "On Contradiction" were published in People's Daily (Renmin ribao, 人民日报) on 29 December 1950, and 1 April 1952, respectively. The worker in front studies "On Practice".