Honore de Balzac described it as a light but stimulating diet, but Barney Zwartz says hope goes to the essence of Easter.

In The Shawshank Redemption , the Tim Robbins character plays Mozart's exquisite Sull'aria over the PA system of a brutal American jail, momentarily transfixing everyone - prisoners and guards - and landing the prisoner Robbins in "the hole" as punishment. Two weeks later, he emerges smiling: "There's something inside they can't touch," he tells his friend Red (Morgan Freeman) about hope.

"Hope?" Red says. "Let me tell you something, my friend. Hope is a dangerous thing. Hope can drive a man insane. It's got no use on the inside." By film's end, Red has recanted. "Hope is a good thing; maybe the best thing," he concludes.

It's an ancient debate: hope as a crucial element of human happiness, or hope as deceiver. It can lead us astray, but it seems we can't live without it.

The classical Greeks saw hope as an illusion, a false consolation. Aristotle called it "a waking dream"; Nietzsche said it was "the worst of all evils, because it prolongs the torments of man". The Roman author Pliny said hope was the pillar that holds up the world. The Duc de la Rochefoucauld, the 17th century French aphorist, summed up the ambiguity: "How deceitful hope may be, yet she carries us on to the end of life."

Perhaps its significance can best be gauged in its negation: despair, hopelessness, fear. And there's plenty of that in 2009, with climate change, the global economic crisis and the disappearance of retirement savings, insecurity about jobs, and natural disasters from bushfires to earthquakes.

For Christians, Easter is of all times the season for hope. The ultimate symbol and cause for hope is commemorated in Christ's resurrection on Easter Sunday, passing from death to life as the "first fruits" and guaranteeing the same transformation for God's people.

The iconic Anastasis depicts the risen Jesus in front of the empty tomb, reaching out with both arms to help from their graves Adam and Eve, who represent all of redeemed humanity. The Bible teaches that the hope of Christ is a hope for all.

Actually, the word covers two related and overlapping but distinct concepts. Ordinary hope, the way the word is generally used, is rooted in expectations for the future, the possibility of positive change. Spiritual faith - the sort central to Christianity, but by no means confined to religion - goes far deeper. It transcends our individual circumstances, rather than depend on them; it is a way of looking at the world, a core attitude.

That's not to minimise the first sort, which, psychiatrist Louise Newman observes, is central in psychological and mental health. "There's been interesting work on the importance of hope as an attitude to the future and whether it promotes resilience," she says. Hope means being able to think about the future hypothetically in a way that generates possibilities. People without any belief in the possibility of change can become depressed, even suicidal, she says.

Small things can provide hope. People find glimmers of hope amid atrocity and great loss.

A Christian clinical psychologist, Chris Brown, thinks hope is often part of human denial. "We are all going to get sick and die, but it's too hard to think about, so we block it out." People cope by living with a degree of alienation, even from ourselves. Brown says courage is as important as hope in facing this. "It's too easy to say 'I believe in Jesus, I've got my divine life insurance plan' - I've still got to live this bit. I have good Christian friends who hope for the afterlife but are miserable now. As Henri Nouwen said, 'eternal life is either now or never.' " (The biblical term "eternal life" refers to a quality of life rather than its duration.) Continued…