Perek ג: Weighing a Life, Weighing a World
The Rambam introduces a striking idea: every person, and the entire world, exists on a constant scale between merit and sin. Who is a Tzaddik, who is a Rasha, and who is in between? This Perek also opens the list of people whose sin isn't easily forgiven, and begins the list of things that can block Teshuva altogether.