On Liturgical Usages

Constantinople IV Eighth Ecumenical Council 879/880

Every Church has certain old usages which it has inherited. One should not quarrel and argue about them. Let the Roman Church observe its usages; this is legitimate. But let also the Church of Constantinople observe certain usages which it has inherited from old times. Let it be likewise so in the Oriental sees. . . . Many things would have not happened if the Churches had followed this recommendation in the past. (Mansi, XVII, Col. 489.)