The reason Lent lasts 40 days is that 40 is the traditional number of judgment and spiritual testing in the Bible (Gn 7:4, Ex 24:18, 34:28, Nm 13:25, 14:33, Jon 3:4).  Lent bears particular relationship to the 40 days Christ spent fasting in the desert before entering into his public ministry (Mt 4:1-11).  We imitate Christ by spending 40 days in spiritual discipline before the celebration of Christ’s triumph over sin and death.

Fasting is a biblical discipline that can be defended from both the Old and the New Testament.  Christ expected his disciples to fast (Mt 9:14-15) and issued instructions for how they should do so (Mt 6:16-18).  We follow this pattern by holding a partial fast on Ash Wednesday and Good Friday.  Abstinence from certain foods is also a biblical discipline.  In Daniel 10:2-3 we read, “In those days I, Daniel, was mourning for three weeks. I ate no delicacies, no meat or wine entered my mouth, nor did I anoint myself at all, for the full three weeks.”  We use a practice similar to Daniel’s when, as a way of commemorating Christ’s Crucifixion on a Friday, we abstain from eating meat on that day of the week during Lent.  The only kind of flesh we eat on Friday is fish, which is a symbol of Christ.

Even the Ash Wednesday practice of having one’s forehead signed with ashes has a biblical parallel.  Putting ashes on one’s head was a common biblical expression of mourning (1 Sm 13:19, Est 4:1, Is 61:3; see also Est 4:3, Jer 6:26, Ez 27:30, Dn 9:3, Mt 11:21, Lk 10:13).  By having the sign of the cross made with ashes on our foreheads, we mourn Christ’s suffering on the cross and our own sins, which made that suffering necessary.