Ifa is the divination system that stands at the intellectual and religious center of Yoruba religion, and it is among the most elaborate oracular systems in the world, so much so that its literary corpus was recognized by UNESCO as a masterpiece of the intangible heritage of humanity. The diviner, a highly trained babalawo ("father of secrets"), consults the oracle either by manipulating sixteen sacred palm nuts (ikin) from hand to hand or by casting a divining chain (opele), and from the results derives one of 256 figures (the odu, produced as combinations of the sixteen basic signs). Each of the 256 odu is the title of an immense body of memorized oral literature, verses, myths, proverbs, and the precedents of past cases, together with the sacrifices (ebbo) each prescribes. The babalawo's art lies not in the mechanical casting but in the years of memorization required to master this corpus and in knowing which verses apply to the questioner's situation. Ifa is understood to speak through Orunmila, the orisha of wisdom and divination, who witnessed the creation and knows the destiny of all beings, and it is consulted at every major juncture of life, birth, naming, marriage, illness, undertaking, to discern a person's path and what must be done to align with it. Carried across the Atlantic, Ifa remains central in the diaspora religions of Cuba and Brazil, and it is studied as one of the great systematized bodies of oral knowledge in world culture.
What the entry above sets out is the public working of the oracle, and that part is public: Nigeria itself put the Ifa divination system forward for UNESCO inscription. What is not set out here is the initiation by which a babalawo enters the office, or the corpus as it is transmitted within that initiation. The initiation is closed. This entry records that it exists, reproduces neither its procedure nor its content, and quotes no odu verse. That a great deal of Ifa material has been printed, by mid-century ethnographers and more recently by people selling access to it, is not evidence that anyone entitled to release it did so. The babalawo entry sets out this position at length.