For the longer to have had to rack your brains for something the more firmly will is stay once you have got it. - Arthur Schopenhauer

Every true thinker for himself is so far like a monarch; he is absolute, and recognises nobody above him. His judgments, like the decrees of a monarch, spring from his own sovereign power and proceed directly from himself. He takes as little notice of authority as a monarch does of a command; nothing is valid unless he has himself authorised it. On the other hand, those of vulgar minds, who are swayed by all kinds of current opinions, authorities, and prejudices, are like the people which in silence obey the law and commands.

It can truly be said: Men are the devils of the earth, and the animals are the tormented souls.

Die Welt als Wille und Vorstellung, Zweiter Band, Ergänzungen zum dritten Buch, para. 36 (1859)