I don't know who said that originally, but it seems very appropriate when applied to modern left-wing idealogy. I wasn't around during the Russian Revolution, but I suspect that Lenin and his followers had the 'peoples' best interests in mind when they overthrew the Czar and installed communism. It seems logical that Stalin later meant to build a better socialist state when he starved millions through his actions, or lack of actions during the 1930's. Hitler's National Socialist Party sought to make life better for Germans by ridding them of their Jewish brethren and by seeking the domination of the western world. Pol Pot and his regime were only trying to build a better 'workers paradise' when they killed as many as 1/7th of their population.
In all of these cases, millions died as a result of government believing it could put to better use private property.
These are only a few of the many examples I can cite of good intentions of the left gone bad. Consider the recent Kelo decision of the US Supreme Court. In that decision, the court's majority held that government can seize private property if government can show that the state (and therefore the people) can gain higher return (through higher tax revenues) from he property if it is turned over to government or a third party for development. How is this view different from that of the notorious leaders discussed above?
That is the problem with so many leftist, progresssive "programs". The basic assumption is that the people are really not smart enough as individuals to "properly" make use of their property and labors, and that only through government action can the needs of the people be met.
That so many on the left think those on the right are none-too-smart is clear; consider the angst of the left in the days following the complete electoral victory of the right at the polls in 2004. Since then the shrillness of the attack on the right from the left has only gotten worse. Given the desparation of the left in these post-election months, it is easy to see how the leaders of the failed socialist regimes of the 20th century felt that it was their duty to rid themselves of those who they felt were clearly not as smart as they, and were therefore a threat to the success of socialism.