Ash Wednesday is a day of repentance and it marks the beginning of Lent. Ashes were used in ancient times, according to the Bible, to express mourning. Dusting oneself with ashes was the penitent's way of expressing sorrow for sins and faults. An ancient example of one expressing one's penitence is found in Job 42:3-6. Job says to God: "I have heard of thee by the hearing of the ear: but now mine eye seeth thee. The other eye wandereth of its own accord. Wherefore I abhor myself, and repent in dust and ashes." (vv. 5-6, KJV) The prophet Jeremiah, for example, calls for repentance this way: "O daughter of my people, gird on sackcloth, roll in the ashes" (Jer 6:26).The prophet Daniel pleaded for God this way: "I turned to the Lord God, pleading in earnest prayer, with fasting, sackcloth and ashes" (Daniel 9:3). Just prior to the New Testament period, the rebels fighting for Jewish independence, the Maccabees, prepared for battle using ashes: "That day they fasted and wore sackcloth; they sprinkled ashes on their heads and tore their clothes" (1 Maccabees 3:47; see also 4:39).
Other examples are found in several other books of the Bible including, Numbers 19:9, 19:17, Jonah 3:6, Matthew 11:21, and Luke 10:13, and Hebrews 9:13. Ezekiel 9 also speaks of a linen-clad messenger marking the forehead of the city inhabitants that have sorrow over the sins of the people. All those without the mark are destroyed.
It marks the start of a 40-day period which is an allusion to the separation of Jesus in the desert to fast and pray. During this time he was tempted. Matthew 4:1-11, Mark 1:12-13, and Luke 4:1-13. While not specifically instituted in the Bible text, the 40-day period of repentance is also analogous to the 40 days during which Moses repented and fasted in response to the making of the Golden calf. (Jews today follow a 40-day period of repenting during the High Holy Days from Rosh Chodesh Elul to Yom Kippur.)
In Victorian England, theatres refrained from presenting costumed shows on Ash Wednesday, so they provided other entertainments.