The century-long predicament of Chinese constitutionalism lies not in its constitutions, but in the complete absence of social contracts as the legitimizing foundation of any constitution. Although the Xinhai Revolution did not shed much blood, it was carried out very much in a way opposed to the spirit of social contract. In less than two years after the establishment of the First Republic, the ill-fated political cooperation between Yuan Shikai and the Nationalist Party was fatally disrupted. The Treaty of Versailles ignited the patriotic fire overnight and set the stage for Communist ascendance. The frequency analysis of keywords from the Xinhai Revolution to the May Fourth Movement showed that anti-contractual concepts such as revolution, Leninism and socialism had been soaring, and had become a popular trend by 1919, leading to the establishment of the Communist regime in 1949.