Origin of Ash Wednesday
Ash Wednesday is Wednesday after Quinquagesima Sunday and marks the first day of the Lenten fast. In the Roman Missal, it bears the name dies cinerum (day of ashes). We find this in the earliest copies of the Gregorian Sacramentary and probably dates from at least the eighth century.
According to ancient tradition, all Catholics are to approach the altar before the beginning of Mass. Then the priest dips his thumb into previously blessed ashes marks upon the forehead (or upon the place of the tonsure in case of clerics ) of each the sign of the cross. He then says: “Remember man that thou art dust and unto dust thou shalt return.” The remains of the blessed palms on the Palm Sunday of the previous year are burnt into ashes used in this ceremony. Ashes are blessed with four ancient prayers, after which they are fumigated with incense and sprinkled with holy water. A priest, usually the highest in the hierarchy of those present, applies ashes on the celebrant himself, be he bishop or cardinal, receives the ashes from either standing or seated. In earlier times, a penitential procession often followed the rite of the distribution of the ashes, but this practice was discontinued.
The custom of distributing the ashes
Undoubtedly, a devotional imitation of the practice observed in the case of public penitents gives birth to the custom of distributing the ashes to all the faithful. However, the reception of a sacramental, which is full of the symbolism of penance in its devotional usage (cf. the cor contritum quasi cans of the “Dies Inn”) dates earlier than was formerly supposed. It is noted as general adherence for both clerics and faithful in the Synod of Beneventum, 1091 (Mansi, XX, 739).
Still, nearly a hundred years earlier than this, the Anglo-Saxon homilist Aelfric thinks that it applies to all classes of men. He says, “We read in the books both in the Old Law and in the New that the men who repented of their sins bestrewed themselves with ashes and clothed their bodies with sackcloth. Let us now do this little at the start of our Lent that we strew ashes upon our heads to indicate that we ought to repent of our sins during the Lenten fast.” He further enforces this suggestion by the horrible illustration of a man who refused to go to church for the ashes on Ash Wednesday. He was accidentally killed in a boar hunt a few days later(Aelfric, “Lives of Saints” ed. Skeat, I, 262-266).
The figurative exclusion from the sacred mysteries symbolized by the hanging of the Lenten veil before the sanctuary possibly reinforced the notion of penance the rite of Ash Wednesday suggests.