What does the Law as a mirror do?
The Law as a mirror reveals what is wrong and needs cleaning up, but it is powerless to cleanse. It shows the problem without providing help or power to change. It is perfect yet weak, condemning but unable to enable obedience.
Les explains that the Law was just like a mirror. When you come in from working in the yard on a hot summer day, sweaty and grimy, you look in the mirror, and all it can do is show you what is wrong and what needs cleaning up. The mirror will never reach out and clean you; it cannot. It is helpless and weak. And that was the Law. It sat there in cold stone, severe, condemning, and did nothing to help a person keep it. It was perfect but powerless. In contrast, the indwelling Holy Spirit is warm, loving, embraces us, and gives us the desire to live pleasing in God's sight, taking away the desire to rebel. That is the work of the Holy Spirit, not us.