Recap: Avatar: The Last Airbender "The Firebending Masters"

"I understand."

Having been accepted by the Gaang, Zuko begins to teach Aang firebending, only to discover that his own firebending has gotten weaker. Realizing that he previously fueled his firebending with hate and rage, Zuko takes Aang to visit the ruins of the ancient Sun Warrior civilization in hopes of learning a new way to firebend.