Quote by Primo Levi
"The truth, once known, cannot be unknown."
More from Primo Levi
"The greater the cruelty, the greater the intelligence required to combat it"
"If understanding is impossible, knowing becomes all the more necessary"
"Monsters exist, but they are too few in number to be truly dangerous. More dangerous are the common men, the functionaries ready to believe and to act without asking questions"
"One single sentence has the power to liberate us from a burden we have carried for a long time"