This is probably WAAAY off topic, even for an off topic discussion, but what I see as the difference between Smith's Wealth of Nations and Marx's Das Kapital is that Smith saw society as constantly evolving, where as Marx's philosophy did not take into account the fact that society would continue to evolve. Hence in the century and a half since Marx penned his manifesto we have seen the rise and demise of communism, while Smith's views of capitalism have continued to evolve to meet the changing needs of society, and have even been embraced by those nations which once extolled the virtues of Marxist doctrine.