Lent is forty days (not counting Sundays) of preparation, patterned on the wilderness fast, and its historical function was catechetical: the season when converts were prepared for baptism at Easter, with the whole congregation fasting alongside them. Modern practice ranges from strict Orthodox rules that exclude animal products entirely to the widespread Western custom of giving up one thing. Ash Wednesday opens it with a sentence — remember you are dust — that is the plainest statement of mortality in Christian liturgy.