To define myth in a single sentence is as foolhardy as to attempt to define poetry—which doesn’t, of course, stop people trying. The definition of myth that has always rung truest for me is that of the filmmaker and anthropologist Maya Deren.

In the 1940s, Maya Deren plunged headfirst into the whirlpool of Haitian voodoo, in an attempt to understand myth from the inside. When she re-emerged—having herself experienced the spirit possession that gave her the title for her book, Divine Horsemen: The Living Gods of Haiti—she wrote that, “Myth is the facts of the mind made manifest in a fiction of matter.”

Voodoo in its various forms is a religion without any formal structure. It is essentially a religion of divine possession, in which the ecstatic dancers circling a post that links earth and heaven are “ridden” by the spirits of the lwa.

Between the sixteenth and nineteenth centuries CE, 12 million black Africans were transported to the Caribbean and North America, where those who survived the terrible journey were enslaved. They included men, women, and children from many different tribes, speaking many different languages. A large proportion were Fon, Yoruba, and Ewe tribespeople, from West Africa’s notorious “slave coast”. They took their gods with them into exile.

In the crucible of slavery, the myths and rituals of these West African peoples fused into a new religion. Kept hidden from the slave-masters, it celebrated the slaves’ African identity, and served as a source of independence and rebellion. In North America and Haiti this religion is called voodoo or vodou; in Brazil, candomblé; in Cuba, santería; in Jamaica, obeayisne; and in Trinidad, shango cult. The word voodoo derives from the Fon vodun, the gods or spirits.

The slaves were forbidden to practice their own rituals, and therefore the voodoo religions took shape under the cover of Christianity. In Haiti, the gods of the Fon, Arada, Nago, Congo, Ibo, Bomba, Limba, and Bambara mingled with those of the Carib Indians who were also enslaved there, to produce voodoo. While Catholic priests have made strenuous efforts to stamp out voodoo, Catholicism is an essential part of voodoo itself. Each of the voodoo gods or lwa is identified with a Catholic saint. Thus Legba the keeper of the crossroads between the human and supernatural worlds is identified with St. Peter and St. Andrew; Azaka the lwa of agriculture with St. Isidore; Gédé, the lwa of the dead, with St. Expedit; Ezili, the lwa of love, with the Virgin Mary.

The fusion of African and Christian beliefs is exemplified in the story of Robert Johnson, “the King of the Delta Blues”. The illegitimate son of a plantation worker, he was born in Hazlehurst, Mississippi, on 8 May 1911—exactly 44 years before me, though Johnson had been dead for nearly 18 years by the time I was born. In his late teens, he started to play the guitar, and hang around with older blues musicians such as Son House and Charley Patton. Son House recalled what a “racket” Johnson made on the guitar. “I’d scold him about it. ‘Don’t do that, Robert. You drive the people nuts. You can’t play nothing.’” Johnson then disappeared from view for a year. When he returned, he was transformed. He had turned from a stumbling novice into an electrifying performer, who left the others open-mouthed, with his haunted eyes, his eerie wail, and his slender fingers fluttering across the frets.

In songs such as “Cross Road Blues”, “Me and the Devil Blues”, and “Hellhound on My Trail”, Robert Johnson hinted at how he had acquired his supernatural skills. He said that he went down to a lonely crossroads at midnight and sold his soul to the Devil in return for musical mastery. This was the moment when he embraced the complex, bitter, rich legacy of his African heritage. For the being Robert Johnson met at the crossroads was not the Biblical Satan, but the West African trickster god of fate, the messenger and mediator between gods and men, who became known in slave religion by his Fon name, Legba.

Among the Yoruba, this god is named Eshu, and his errand boys are precisely the muses invoked by the blues: “Death, Disease, Loss, Paralysis, Big Trouble, Curse, Imprisonment, Affliction.”

Many characteristics of African music persist in the blues, for instance the flattened thirds and fifths referred to as “blue notes”. In the case of Robert Johnson, the African influence is particularly noticeable in the way his instrument seems to come alive to answer and respond to his vocal performance. And the supernatural source of his inspiration would be perfectly familiar to an African musician—for instance Mali’s Ali Farka Touré tells how, “It was the spirits who gave me the gift.”