- How do I know the good side from the bad?
- You will know when you are calm, at peace, passive.

Luke Skywalker (Mark Hamill), Jedi Master Yoda, Yoda (Frank Oz)

10 seconds sound clip from the Star Wars: Episode V - The Empire Strikes Back movie soundboard.

You can hear this line at 01:01:53 in the Blu-ray version of the movie.

Quote context

[...]

- Run! Yes! A Jedi's strength flows from the Force.

- But beware of the dark side. Anger, fear, aggression...

- The dark side of the Force are they, easily they flow, quick to join you in a fight.

- If once you start down the dark path, forever will it dominate your destiny. Consume you it will, as it did Obi-Wan's apprentice. Vader.

- Is the dark side stronger?

- No, no. No. Quicker, easier, more seductive.

- How do I know the good side from the bad?

- You will know when you are calm, at peace, passive.

- A Jedi uses the Force for knowledge and defense, never for attack.

- But tell me why I can't...

- No, no. There is no why. Nothing more will I teach you today. Clear your mind of questions.

- Hmm... Mmm...

[...]