the first day of Lent see also Shrove Tuesday See related entries: Religious holidays and festivals Culture Traditionally, Roman Catholics go to church on Ash Wednesday and their foreheads are marked with ashes as a sign that human bodies become dust. In the US this tradition is still widely followed. The ashes are not washed off but left to go away on their own. It is polite not to make a comment on the mark on a person's forehead. Word Originfrom the custom of marking the foreheads of penitents with ashes on that day.