Quattuor abhinc annos (Latin for "four years ago") is the incipit of a letter that the Congregation for Divine Worship and the Discipline of the Sacraments sent on 3 October 1984 to presidents of episcopal conferences. concerning celebration of Mass in the Tridentine form. The Congregation thereby granted diocesan bishops an "indult" to authorize celebration of the Tridentine Mass according to the 1962 Roman Missal by specified priests and groups of the faithful who requested it. The permitted Tridentine Masses were to be in full accord with the 1962 Missal and in Latin.