Tradition and Lucas de Tuy’s Chronicon Mundi say that according to prayers to St Isidore, in 1158 “...rain fell in abundance on the fields of León and the surrounding area”.
In thanks for this and other later miracles, the city, represented by its corporation, goes voluntarily to St Isidore’s Basilica once a year to offer a large candle weighing about 11 kilos and two other large candles. In the cloister, the canons accept the present, but make it clear that that the offering is an obligation, which the corporation denies. Because of this discrepancy the representatives of the two institutions begin an exchange of opinions and parade their respective speech-making abilities. It ends in a draw, and the argument is put off until the following year.
The three overdone bows which the councillors make before taking leave of the Basilica Chapter have given rise to the popular name of the ceremony: Las Cabezadas (“The Nods”), much more common than its official name of Foro u Oferta (“Obligation or Offering”).