Who is your trust in, yourself or God?
Prayer is used as the framework in this parable for us to understand where we place our trust.
We can meet God as a justified person or as a debtor.
What standard do you live your life by? The pharisee measures how far away he is from others beneath him, but the tax collector measures how far away he is from God's standard.
The tax collector recognises that he cannot repay his debt, and that he needs mercy from God.