(The entrance frozes over, Petro breaks through it…)

Ganodi: How did he break the ice?

Master Yoda: Only water made solid was the door. Easy to break if you have the will.

Katooni: You-you said we would be trapped.

Master Yoda: Not by the cave you were but by your mind.

From Star Wars: The Clone Wars – Season 5 Episode 6: ‘The Gathering’ (5×06) | Produced by Lucasfilm