It is better to endure pain and stay awake, and it is better to endure pain and think than not to think. -Zweig

Only when knowledge comes from positive thinking, not memory, is it true knowledge. -Tolstoy

To be a truly educated person, you must have three qualities: profound knowledge, thinking habits and noble sentiments. Not much knowledge is ignorance; Not used to thinking about whether it is rude or stupid; Without noble sentiments, it is vulgar. Chernyshevski