I've written about liturgy before. Here's another lovely take on it:
Liturgy, at its best, is more like the tracks of the train than the whistle. It’s silent and sturdy and, though almost unnoticed, it leads us to where our hearts long to go. In perhaps the most quoted address on liturgy, C.S. Lewis states, that liturgy is most useful “when, through long familiarity, we don’t have to think about it. As long as you notice, and have to count, the steps, you are not yet dancing but only learning to dance. A good shoe is a shoe you don’t notice. Good reading becomes possible when you need not consciously think about eyes, or light, or print, or spelling. The perfect church service would be one we were almost unaware of; our attention would have been on God.…from Tish Harrison Warren, a priest in the Anglican Church in North America, in a piece on her discovery and appreciation for the church calendar in Christianity Today's excellent "Her.meneutics" here.
Liturgy's trustworthy tracks, along with the church calendar, keep our worship and personal devotions on course as, year after year, they carry us along through the story of Jesus from Advent through Easter and a focus on discipleship for the rest of the year. The accompanying lectionary ensures that we are all, including preachers, at least exposed to themes with which we might not otherwise be inclined to engage.