Mao Zedong. The four-word policy of hard work was put forward by Mao Zedong. 1February, 939, Mao Zedong put forward the slogan of "Do it yourself" at the production mobilization meeting in Yan 'an, aiming at the increasingly serious economic difficulties in the base area. Then the base areas gradually launched a large-scale production movement. Do it yourself, have plenty of food and clothing, as the base areas to overcome economic difficulties and achieve the goal of self-sufficiency in production.