In the extraordinary form of the Roman Rite, the next three days (Monday through Wednesday) are minor rogation days leading up to Ascension Thursday. Rogation days were instituted as:
Days of prayer, and formerly also of fasting, instituted by the Church to appease God’s anger at man’s transgressions, to ask protection in calamities, and to obtain a good and bountiful harvest, known in England as “Gang Days” and “Cross Week”, and in Germany as Bittage, Bittwoche, Kreuzwoche.
The days were distinguished as Major or Minor Rogation days:
The Rogation Days are the 25th of April, called Major, and the three days before the feast of the Ascension, called Minor. The Major Rogation, which has no connexion with the feast of St. Mark (fixed for this date much later) seems to be of very early date and to have been introduced to counteract the ancient Robigalia, on which the heathens held processions and supplications to their gods. St. Gregory the Great (d. 604) regulated the already existing custom. The Minor Rogations were introduced by St. Mamertus, Bishop of Vienne, and were afterwards ordered by the Fifth Council of Orléans, which was held in 511, and then approved by Leo III (795-816). This is asserted by St. Gregory of Tours in “Hist. Franc.”, II, 34, by St. Avitus of Vienne in his “Hom. de Rogat.” (P.L., LVIII, 563), by Ado of Vienne (P.L., CXXIII, 102), and by the Roman Martyrology. Sassi, in “Archiepiscopi Mediolanenses”, ascribes their introduction at an earlier date to St. Lazarus. This is also held by the Bollandist Henschen in “Acta SS.”, II, Feb., 522. The liturgical celebration now consists in the procession and the Rogation Mass. For 25 April the Roman Missal gives the rubric: “If the feast of St. Mark is transferred, the procession is not transferred. In the rare case of 25 April being Easter Sunday [1886, 1943], the procession is held not on Sunday but on the Tuesday following”.
In light of the attacks against the priesthood, mothers (see Mother’s Day: Let’s Celebrate the Pill) and sexuality (see Washington Post: Get Rid of Virginity) let us use these days to invoke the Father’s protection and appease His anger towards a people who continues to harden their hearts.
For more information on Rogation Days, see the article at the Fisheaters Web site.
 Mershman, Francis. “Rogation Days.” The Catholic Encyclopedia. Vol. 13. New York: Robert Appleton Company, 1912. 10 May 2010 <http://www.newadvent.org/cathen/13110b.htm>.