"What luck for rulers, that men do not think." Adolph Hitler.
"If everyone is thinking alike, someone isn't thinking." George Patton
"This is slavery, not to speak one's thought." Euripides
"Learning without thought is labor lost." Confucius
"Nothing pains some people more than having to think." Martin Luther King Jr.
"Rarely do we find men who willingly engage in hard, solid thinking. There is an almost universal quest for easy answers and half-baked solutions." Martin Luther King Jr.
"To think is to differ." Clarence Darrow
"I'll be more enthusiastic about encouraging thinking outside the box when there's evidence of any thinking going on inside it." Terry Pratchett
"Where all think alike, no one thinks very much." Walter Lippman
"The moment we want to believe something, we suddenly see all the arguments for it, and become blind to the arguments against it." George Bernard Shaw
"Thinking is the hardest work there is, which is the probable reason why so few engage in it." Henry Ford
"Thinking is more precious than all five senses." Nachman of Bratslav
"A great many people think they are thinking when they are merely rearranging their prejudices." William James