Tuesday's book challenge question

This quote was taken from a movie created from book three in a famous series of novels. Part of this quote is the title of one of the chapters in the book. Name the author of the quote, and the title of the book. Hint: A new book in this series was just released.

"Happiness can be found, even in the darkest of times, if one only remembers to turn on the light."

Put your answers in the comments for a chance to win a prize on Tuesday!