Every year, on the Wednesday following Palm Sunday, Catholics receive the ashes of the previous year's palms as a blessing, traced into the form of a cross on their foreheads.These ashes symbolize the dust from which humankind came, and the dust to which we all shall return, a concept familiar to many people through the phrased "ashes to ashes, dust to dust."By using the ashes of the previous year's palms, the ashes come to symbolize both the joy of Christ's entry into Jerusalem and the regret over His sacrifice.Ashes were once a symbol of both penance and mourning.At the time Christ lived, both were expressed by sitting in dust and ashes, as well as placing dust and ashes on one's forehead.