The ``July 21st Directive'' refers to a statement Mao Zedong added to the final proof of the editor's note to ``The Road of Training Engineering and Technical Personnel as Demonstrated by the Shanghai Machine Tool Plant -- an Investigation Report'', carried by Renmin Ribao on July 21, 1968. The directive said, ``It is still necessary to have universities; here I refer mainly to colleges of science and engineering. However, it is essential to shorten the length of schooling, revolutionize education, put proletarian politics in command and take the road of the Shanghai Machine Tool Plant in training technicians from among the workers. Students should be selected from among workers and peasants with practical experience, and they should return to production after a few years' study.''