“True friends are always together in spirit. (Anne Shirley)”
― L.M. Montgomery, 

“The man of knowledge must be able not only to love his enemies but also to hate his friends.”
― Friedrich Nietzsche

“Do I not destroy my enemies when I make them my friends?”
― Abraham Lincoln

“I don't know half of you half as well as I should like; and I like less than half of you half as well as you deserve.”

“There is no friend as loyal as a book.”

“It takes a great deal of bravery to stand up to our enemies, but just as much to stand up to our friends.” 

“Good friends, good books, and a sleepy conscience: this is the ideal life.”
― Mark Twain