The final paragraph of Joshua Muravchik's Heaven on Earth: The Rise and Fall of Socialism:
By no means all socialists were killers or amoral. Many were sincere humanitarians; mostly these were the adherents of democratic socialism. But democratic socialism turned out to be a contradiction in terms, for where socialists proceeded democratically, the found themselves on a trajectory that took them further and further from socialism. Long before Lenin, socialist thinkers had anticipated the problem. The imaginary utopias of Plato, Moore, Campanella and Edward Bellamy, whose 1887 novel, Looking Backward, was the most popular socialist book in American history, all relied on coercion, as did the plans of The Conspiracy of Equals. Only once did democratic socialists manage to create socialism. That was the kibbutz. And after they had experienced it, they chose democratically to abolish it.
The dictatorship of the proletariat. What a concept!