Guillén's poem evokes a ritual Afro-Caribbean chant performed while killing a snake:
- Canto para matar una culebra
- La culebra tiene los ojos de vidrio
- la culebra viene y se enreda en un palo
- Con sus ojos de vidrio, en un palo
- Con sus ojos do vidrio
- La culebra camina sin patas
- La culebra se esconde en la yerba
- Caminando se esconde en la yerba
- Caminando sin patas
- (and so on)
Revueltas first set the poem to music in Mexico City in 1937, originally for small orchestra. In 1938, he expanded it into a full-scale orchestral work for 27 wind instruments, 14 percussion instruments, and strings. As one advertising blurb for the score describes it:
The work begins with a slow trill in the bass clarinet as the percussion plays the sinuous, syncopated rhythm that drives the work. Soon a solo bassoon enters playing an eerie but rhythmic ostinato bassline. The tuba then enters playing the first of this work's two major themes, a muscular, ominous motif. Other brass join in to play the theme, growing louder and more emphatic, but rigorously yoked to the underlying rhythm. Eventually the horns blast as loudly as they can, with obsessive trills on the low clarinets far underneath, and the strings enter with the slashing second theme. The brass take up this new theme and bring it to a climax, after which the music returns to its opening texture. This recapitulation brings with it a mood of foreboding. The rhythm becomes even more obsessive, and finally the music reaches a massive climax during which both themes are played, overlapping, sometimes in part and sometimes in whole, by the entire orchestra in what sounds like a musical riot. The coda feels like the final dropping of a knife.
Sensemayá is based on Afro-Cuban religious cults, preserved in the cabildos, self-organized social clubs for the African slaves. African religions were transmitted from generation to generation. These religions, which had a similar but not identical structure, were known as Lucumi or Regla de Ocha if they derived from the Yoruba, Palo from Central Africa, Vodú from Haiti, and so on. In this poem we meet an adept known as the mayombero. He is knowledgeable in the area of herbal medicine, as well as being the leader of rituals. In Sensemayá, the mayombero leads a ritual which offers the sacrifice of a snake to a god, perhaps Babalu Aye. This god, popularized as Babalu in the United States by Desi Arnaz, is the Afro-Cuban spirit who has the power to heal, or spread pestilence. One of the main motives in Sensemayá is based on this word mayombero. This chant "mayombe, bombe mayombé", is an example of Guillén's use of repetition, derived from an actual ceremony.
The score calls for a symphony orchestra thus made:
- woodwinds: 2 piccolos, 2 flutes, 2 oboes, an English horn, a piccolo clarinet in E-flat, 2 soprano clarinets in B-flat, a bass clarinet, 3 bassoons, a contrabassoon;
- brasses: 4 horns in F, 4 trumpets in C, 3 trombones and a tuba;
- timpani and percussion (3 players): xylophone, claves, maracas, raspador, gourd, small Indian drum, bass drum, 2 tom-toms (high and low), cymbals, 2 gongs (large and small), a glockenspiel;
- keyboards: a celeste, a piano;
- strings: violins (1st and 2nd), violas, violoncellos and basses.
- Dean, Jack Lee. 1992. "Silvestre Revueltas: A Discussion of the Background and Influences Affecting His Compositional Style". Ph.D. thesis. Austin: University of Texas at Austin.
- Hoag, Charles K. 1987. "Sensemayá: A Chant for Killing a Snake." Latin American Music Review / Revista de Música Latinoamericana 8, no. 2 (Autumn): 172–84.
- Jacobs, Glenn. Cuba's Bola de Nieve: A Creative Looking Glass for Culture and the Artistic Self. Latin American Music Review / Revista de Música Latinoamericana 9, no. 1 (Spring–Summer): 18–49.
- Kaufman, Christopher. 1991. "Sensemayá: The Layer Procedures of Silvestre Revueltas". DMA thesis. Ithaca, New York: Cornell University.
- Mayer-Serra, Otto. 1941. "Silvestre Revueltas and Musical Nationalism in Mexico." Musical Quarterly 27:123–45.
- Zohn-Muldoon, Ricardo. 1998. "The Song of the Snake: Silvestre Revueltas' Sensemayá." Latin American Music Review / Revista de Música Latinoamericana 19, no. 2 (Autumn): 133–59.
- Text of the poem (English and Spanish)
- Sensemayá on YouTube
- Revueltas's Sensemayá, Leonard Bernstein's marked copy of the published study score (Schirmer). Leon Levy Digital Collection: International Era 1943–1970. New York Philharmonic Digital Archive (Accessed 6 July 2012).
- Revueltas's Sensemayá, Leonard Bernstein's marked copy of the manuscript full score. Leon Levy Digital Collection: International Era 1943–1970. New York Philharmonic Digital Archive (Accessed 6 July 2012).