May 5 marks the birthday of Karl Marx. Best known as the author of "Capital" and, with Freidrich Engels, the "Communist Manifesto," Marx provided the intellectual foundation for an array of regimes that at one time governed nearly half of Earth's population.

These regimes were, for many, a long nightmare of state terror, genocides, deportations, extrajudicial executions, forced labor, and artificial scarcity, crimes that left tens of millions of people dead and deprived many more of basic dignity.

But while Marx's solutions are widely and, in some cases, rightfully, condemned, his analysis of the capitalist mode of production still resonates among workers and intellectuals alike around the world. As much of the globe struggles to extricate itself from an economic slowdown that many believe was created by the excesses of what Marx called "the bourgeoisie," several Marxist concepts – the anarchic nature of capitalism, the parasitism of the financial class, and the reserve army of the unemployed, to name a few – appear to take on new relevance.

Here are 10 quotations from Marx. Let us know which ones you like best, and add your favorites that didn't make it into the list in the comments below.