When we've done wrong, a Reflection on Psalm 51

Psalm 51 is one of seven penitential psalms. I'm wondering why only seven. How often do we need words to express our recognition that we need to be forgiven?

The first seven verses ask for forgiveness. Sometimes, we need reminders that we are sinning. And, sometimes, we are so burdened by our sins that we need reminders that God is compassionate.

We can pray Psalm 51 when we recognize that we need forgiveness, that we want forgiveness. And we can pray Psalm 51 when we want what forgiven people have--restoration.