Who said "I don't know what you are, Mr. Ai, but I know what you aren't"?

This quote is attributed to Estraven.

I don't know what you are, Mr. Ai, but I know what you aren'... - Estraven

"I don't know what you are, Mr. Ai, but I know what you aren't"

Estraven Truth

Character in The Left Hand of Darkness

Buy "The Left Hand of Darkness" on Amazon

"One cannot simply walk away from one's kethil."

"Winter is the time for stories, not for traveling."

"Forsivin! I had no forgiveness coming."

"Love is a country where borders are dreams."

"Lucy, you got some 'splainin' to do!"

"You must always be honest with the people you love."

"Truth always comes out in the end."

"Honesty is always the best policy."