Obi-Wan Kenobi: You have allowed this dark lord to twist your mind, until now, until now you've become the very thing you swore to destroy.
Anakin Skywalker: Don't lecture me, Obi-Wan! I see through the lies of the Jedi. I do not fear the dark side as you do. I have brought peace, freedom, justice, and security to my new Empire.
Obi-Wan Kenobi: Your new Empire?
Anakin Skywalker: Don't make me kill you.
Obi-Wan Kenobi: Anakin, my allegiance is to the Republic, to democracy.
Anakin Skywalker: If you're not with me, then you're my enemy.
Obi-Wan Kenobi: [realizing that Anakin is consumed by evil and there's no reasoning with him anymore] Only a Sith deals in absolutes.
[draws his lightsaber]
Obi-Wan Kenobi: I will do what I must.
Anakin Skywalker: You will try.