This from a wonderful interview with Sam Wells , where he is discussing some of the ideas in his Improvisation: The Drama of Christian Ethics . It’s one of the best answers to “Why liturgy?” that I’ve come across. The remainder of this post is quoted from that interview:

“Life is a rehearsal. If we really think heaven is what we say we believe it is, then life actually is a rehearsal for that. So if you think in terms of the five-act play — creation, Israel, Jesus, church and eschaton — and of us in Act 4, then Act 4 is really a rehearsal for Act 5. Act 5 is the eternal one. That’s everlasting life.

“So, the habits of rehearsal are everything we do in life, and I’m very affected by a lot of stories that encourage me in the belief that most of my life is preparation for crucial moments. I’m not saying I’ve reached a defining moment in my life, but I’ve reached some fairly crucial moments where I had to act from memory . . . .

“You’re in a hospital, you’re holding the hand of an 82-year-old woman. All her family are around the intensive care unit, and you know that they’ve just unhooked the machines, so she’s got 45 minutes until she’s going to stop breathing. How do you fill that 45 minutes? That’s what you go to seminary for, to know how to fill that 45 minutes.

“I’d say the first thing you do is you sing. You recall something that has been significant in the worshipping life of everybody there, and you sing that, and it puts you in touch with good things about the richness that this woman has brought to everybody’s life. And it’s also a prayer, but it’s a prayer that you know that the woman maybe can still hear, because hearing and touch are really among the last senses to go.

“So if you’d never learned that hymn - in other words, if you hadn’t rehearsed - how could you ever sing it? So you think, ‘Well, why do we go - as you say to teenagers - why do we go every Sunday and we sing the same boring old hymns?’

“Well, there’s an answer for you: because one day you’ll be in hospital with an 82-year-old woman — and it could be me, actually, that woman — and you’ll have 45 minutes until she dies, and you’ll be gathered around with everybody, and everyone will be weeping but wanting something important, and you’ll think, ‘Well, that’s why we sang those hymns, wasn’t it?’”