After the Mexican Revolution (1910-1917), post-revolutionary governments sought to educate the public on the principles of social justice, as consecrated in the new constitution. Mural painting became an extraordinary visual vehicle, for occupying public spaces like government buildings, schools and markets where it was accessible to all people and spoke even to the illiterate, in contrast to traditional easel painting aimed at private art consumption by the educated. During the government of President Alvaro Obregon (1921-1924) mural painting was actively promoted by Minister of Education Jose Vasconcelos. Diego Rivera's strong personality and political connections led to many important early commissions. His first commission from Vasconcelos was to paint a mural in the Preparatory School, where four young artists dared to accept Vasconcelos' challenge. Jean Charlot was one of them, and also his friend and roommate Fernando Leal who invited him to get involved. Charlot's fresco "Massacre in the Templo Mayor" (1921–1922) is in front of Fernando Leal's "The Dancers of Chalma" (1921–23). In his fresco Charlot portrayed himself, Leal and Diego Rivera. Charlot's was the first mural finished and the first in the fresco technique." "Thus, Charlot participated in the founding of Mexican muralism."