From Darkness at Noon by Arthur Koestler:
Ivanov smiled. 'Maybe,' he said happily. Look at the Gracchi and Saint-Just and the Commune of Paris. Up to now, all revolutions have been made by moralizing dilettantes. They were always in good faith and perished because of their dilettantism. We for the first time are consequent. ...'
'Yes,' said Rubashov. 'So consequent, that in the interests of a just distribution of land we deliberately let die of starvation about five million farmers and their families in one year. So consequent were we in the liberation of human beings from the shackles of industrial exploitation that we sent about ten million people to do forced labour in the Arctic regions and the jungles of the East, under conditions similar to those of antique galley slaves. So consequent that, to settle a difference of opinion, we know only one argument: death, whether it is a matter of submarines, manure, or the Party line to be followed in Indo-China. Our engineers work with the constant knowledge that an error in calculation may take them to prison or to the scaffold; the higher officials in our administration ruin and destroy their subordinates, because they know that they will be held responsible for the slightest slip and be destroyed themselves; our poets settle discussions on questions of style by denunciation to the Secret Police, because the expressionists consider the naturalistic style counter-revolutionary, and vice-versa.' ...
In later life Koestler might have had some daft ideas about science but back in the late 1930's he was right on the ball when it came to the Stalin's Soviet Union. For a book on such a grim subject, Darkness at Noon is a surprisingly easy read.