From: EWTN.com
The liturgical use of ashes originated in the Old Testament times. Ashes symbolized mourning, mortality and penance. In the Book of Esther, Mordecai put on sackcloth and ashes when he heard of the decree of King Ahasuerus to kill all of the Jewish people in the Persian Empire (Esther 4:1). Job repented in sackcloth and ashes (Job 42:6). Prophesying the Babylonian captivity of Jerusalem, Daniel wrote, "I turned to the Lord God, pleading in earnest prayer, with fasting, sackcloth, and ashes" (Daniel 9:3).
Jesus made reference to ashes, "If the miracles worked in you had taken place in Tyre and Sidon, they would have reformed in sackcloth and ashes long ago" (Matthew 11:21).
In the Middle Ages, the priest would bless the dying person with holy water, saying, "Remember that thou art dust and to dust thou shalt return."
The Church adapted the use of ashes to mark the beginning of the penitential season of Lent, when we remember our mortality and mourn for our sins. In our present liturgy for Ash Wednesday, we use ashes made from the burned palm branches distributed on the Palm Sunday of the previous year. The priest blesses the ashes and imposes them on the foreheads of the faithful, making the sign of the cross and saying, "Remember, man you are dust and to dust you shall return," or "Turn away from sin and be faithful to the Gospel." As we begin this holy season of Lent in preparation for Easter, we must remember the significance of the ashes we have received: We mourn and do penance for our sins. We again convert our hearts to the Lord, who suffered, died, and rose for our salvation. We renew the promises made at our baptism, when we died to an old life and rose to a new life with Christ. Finally, mindful that the kingdom of this world passes away, we strive to live the kingdom of God now and look forward to its fulfillment in heaven.
Almighty and everlasting God, you despise nothing you have made and forgive the sins of all who are penitent.
Create and make in us new and contrite hearts, that we, worthily lamenting our sins and acknowledging our brokenness, may obtain of you, the God of all mercy, perfect remission and forgiveness; through Jesus Christ our Lord, who lives and reigns with you and the Holy Spirit, one God, for ever and ever.
Amen.
Amen.