Bill Clinton is undoubtedly a clever man. And his presidency was not terribly ideological. His good-natured "triangulating" (compromise) is a stark contrast with the unbending righteous Leftism of Obama. So it is possible that he did have some wise things to say. One that has a certain plausibility is something he said at the opening of his library:
“The Left at its best tears down walls that shouldn’t have been there, and the right at its best stops the left from tearing down walls that should be there.”
It may not have been original to him but it is a pretty good bit of triangulating, whatever else it is. The key is the expression "At its best". When is the Left at its best? I imagine that what would mostly spring to mind in that connection would be the succour that the Left gives to the poor. It could be argued that welfare measures are needed to keep social peace. If the poor were left to starve they might be more criminal, more likely to mount an armed rebellion etc.
But here's the catch: Social welfare measures such as old-age pensions, workers' compensation, limited working hours etc were NOT Leftist initiatives. They were first introduced by Otto von Bismarck in Germany, the reactionary "Iron Chancellor" of Prussia. And he was followed not long after that by Benjamin Disraeli, the much respected Conservative Prime Minister of Great Britain and Ireland at the height of the British empire in the late 19th century. And there has been a broad consensus ever since that at least some government welfare measures are necessary.
So I am at a loss to know what Leftists have originated that could be described as "best". Is their current promotion and valorization of homosexuality "best"? It might gain them a few votes among homosexuals but alienates a lot of Christians. Don't they matter? The legalization of homosexuality was certainly an act of kindness but in the USA that has been primarily the work of the courts rather than of either political party.
And the 1964 Civil Rights Act aimed at benefiting blacks got more congressional support from Republicans than it did from Democrats.
So if someone can point me to beneficial Leftist destruction, I would be all ears.