History, in Marx's view, was nothing but the crashes and grinding of these material forces. There was no such thing as a fixed human nature.

Marx said the expropriated working classes must take back what is rightfully theirs from the exploiting capitalist classes.

Benedict sums the fundamental error with Marx neatly:

"He showed precisely how to overthrow the existing order, but he did not say how matters should proceed thereafter. He simply presumed that with the expropriation of the ruling class, with the fall of political power and the socialization of means of production, the new Jerusalem would be realized. Then, indeed, all contradictions would be resolved, man and the world would finally sort themselves out."

Having accomplished the revolution in Russia, Vladimir Lenin must have realized that the writings of the master gave no indication as to how to proceed. Marx had only spoken of the interim phase of the dictatorship of the proletariat as a necessity which in time would automatically become redundant.

What resulted is that millions of Russians died in famine and wholesale slaughter. It became clear to Lenin that he had to back away, lest there be no one left to rule. But the dictatorship continued. So too did the poverty relative to capitalist nations.

So the pope has put the problems of economics exactly in the right light: The practical issue needs to be settled within a sound morality and understanding of human nature. Socialism fails because it has no system for pricing factors of production to make economic calculation possible. Prices come from the exchange of the very private property with which socialism dispenses.

And yet the moral problem with socialism is more profound: It exalts theft as an ethic and overlooks the human right of freedom.

Would that every Catholic interested in economics would read this encyclical. Some are getting the message already: The Catholic Church in Venezuela worked against Hugo Chavez's dangerous plan for nationalization and regimentation of economic life. Someday, the world will come to learn the lessons that the history of socialism has taught.