Harry Potter and the Half-Blood Prince

"The past lives in us all."

"To know him is to understand why he must be stopped."

"Half measures are worthless in matters of life and death."

"Regret is a powerful emotion."

"The human psyche is a curious instrument."

"Fame is a fickle friend."

"We must always choose between what is right and what is easy."

"Arrogance and stupidity are not the same thing, though they often look identical."

"There are some things more important than living."

"I love being back at Hogwarts. It's the only place that's ever felt like home."

"The castle is fully protected against those who have no business being within its walls."

"We are only as strong as we are united, as weak as we are divided."

"To one as young as you, I'm sure it feels like an eternity."

"Tom Riddle was not, and is not, a man to feel affection for anyone."

"Horcruxes are among the foulest objects that walk this earth."

"Severance, not mere death, is what we seek."

"Wandless magic is a rare and difficult skill."

"It is natural to want power, I understand that."

"Books and quills, that's all anyone cares about at Hogwarts."

"Greatness inspires envy, envy engenders spite, spite spawns lies."

"The Dark Lord has gone, though not... not as we might have hoped."

"If the adult wizards of tomorrow lose faith in institutions such as Hogwarts, we might as well board up the castle now."

"One cannot be a true believer in democracy and also believe that half your countrymen are inherently subhuman."

"I have already told you. It is our choices that show what we truly are, far more than our abilities."

"Voldemort himself created his worst enemy, just as tyrants always do."

"Dark and difficult times lie ahead. Soon we must all face the choice between what is right and what is easy."

"It is our choices that show what we truly are, far more than our abilities."

"But you are, I think, both brave and clever enough to overcome anything."

"We could end this, you know."

"You are not as helpless as you feel, Harry."