The ese are the content of Ifa. Each of the 256 odu — produced by the sixteen binary positions cast twice — carries a body of verses, and estimates of the total corpus run into the tens of thousands. Each ese has a standard structure: the name of the diviner who was consulted, the client, the matter brought, the prescribed offering, whether the client complied, and the outcome, usually followed by a song. The consultation therefore works by precedent rather than by interpretation: the babalawo casts, identifies the odu, and recites the verses belonging to it, and the client identifies which situation matches theirs. The diviner is not supposed to be told the question in advance, which is the system's internal check. Because the corpus is enormous and each ese carries its own prescriptions and prohibitions, mastery is a matter of years, and the extent of a babalawo's repertoire is the measure of his standing.