I have a two friends who have taken a class on the book of Leviticus this semester, and one of their assignments last week was to live according to Levitical law. They needed to wear clothes all of one fabric, not touch dead things, not eat meat and cheese in the same meal, etc. I really don't know all that was entailed. They both said they had to be consciously aware of the state of their hearts.
After a conversation with Emily (one of the participants), I have had something she said rolling around in my head. She became aware that it is impossible for a person to remain "clean". If you touch someone who is unclean (and you have no real way of knowing), you are unclean. You can live under the assumption that, try as you may, at the end of the day you will need to rinse off because of uncleanliness. God has made extremely difficult, under his own law, for his people to be clean.
This may sound defeating, but instead it's somehow freeing. It makes us acutely aware of how much we need God's forgiveness. We cannot make it on our own. Forgiveness draws us back into relationship with God, unable to deny that we don't need him. God has always been about relationship with his people, and since the fall we've been running away trying to be our own god. Through his law he put in place a reminder system.
Emily also mentioned that if we examine what the underlying principles are behind the law, we see the character and heart of God. It was never intended to be about dos and don'ts, but about being set apart in our character and hearts.
Thankfully, now we can slap some cheese on our burgers, and hug our friends after they have handled dirty diapers. We don't have to rinse off anymore at the end of the day, because we are marked with the Holy Spirit to remind us of our need for repentance and for God. And that same Spirit is transforming our hearts that we might one day know and we are fully known.