The Great Terror
"Stalin was a very distrustful man, sickly suspicious. We know this from our work with him. He could look at a man and say: “Why are your eyes so shifty today?” or “Why are you turning so much today and avoiding to look me directly in the eyes?” The sickly suspicion created in him a general distrust even toward eminent Party workers whom he had known for years. Everywhere and in everything he saw 'enemies,' 'two-facers' and 'spies.' Possessing unlimited power, he indulged in great willfulness and stifled people morally as well as physically. A situation was created where one could not express one’s own volition."
-Nikita Khrushchev, Joseph Stalin's successor