Why do we do that in church...?

Here is a great post on Basic Principles for Liturgical worship from Derek Olson at the Haligweorc blog.  Why do we say and pray (and sing) some of the same things each and every week?  Why do other parts of the service change?  What are we trying to accomplish when we get together on Sunday mornings? 

There is actually a deep logic and reason for the things that we Methodists, Lutherans, Anglicans, Roman Catholics, Eastern Orthodox and others do each and every Sunday, and this post discusses and explains some of them really well.  The Post examines these basic aspects of liturgy: Adoration; Formation; Repetition; Variation; Continuity; and Stability.