Explanation of Rogation Days

Earthquakes and other calamities afflicted the diocese of Vienne in Dauphiny (France) in the fifth century, and Saint Mamertus, who was Bishop of that Diocese, instituted a penitentiary procession with public applications on the Monday, Tuesday, and Wednesday before Ascension Day.  In 816, Pope Leo III introduced it into Rome, and soon after it became a general observance throughout the Church. The Litany of the Saints, the Psalms and Prayers sung during the Procession on these days are supplications: hence the name of ‘Rogation Days’ (rogare, to ask) applied to them.  The object of these rotation applications is to appease the anger of God and avert the scourges of His justice, and to pray for the harvest.