If you emerge from that sad place with thoughts of hatred and of wrath against mankind, you are deserving of pity; if you emerge with thoughts of good-will and of peace, you are more worthy than any one of us.
The Bishop talks to Valjean as someone who understands what punishment can carve into the heart. He lays out two possible futures and sets them side by side, hatred and peace. The juxtaposition is calm, and that calmness itself feels like mercy. He calls hatred pitiable because it traps the sufferer, even when it feels justified. Then he honors peace as the harder victory, the one that deserves real respect. The emotion is philosophical because he is thinking about what suffering does, not just what it looks like. It resonates for anyone trying to keep their heart from hardening after being hurt.