Guillen, one of the leaders of the Afro-Antillean school of poetry, was inspired by popular dance, ballads, song rhythms, and speech patterns, all of which show a heavy African influence. In his first volumes, Motives of Sound (1930) and Songoro Cosongo (1931), meaning is communicated primarily through sound, and many poems are in regional popular dialect. Much of his subsequent poetry reflects his profound social commitment: West Indies Limited (1934) opposes imperialism, and Spain (1937) expresses his support for the republic during the Spanish civil war. Tengo (1964) deals with the Cuban Revolution in a tone aimed at a popular audience. All Guillen's work is an intense effort to relate poetry to the culture of the Cuban people and to political and social protest.