Experience praises the most happy the one who made the most people happy.

The product of mental labor - science - always stands far below its value, because the labor-time necessary to reproduce it has no relation at all to the labor-time required for its original production.

Natural science will in time incorporate into itself the science of man, just as the science of man will incorporate into itself natural science: there will be one science.

Religion is the sigh of the oppressed creature, the heart of a heartless world, and the soul of soulless conditions. It is the opium of the people.

Religion is the opium of the masses.

On a level plain, simple mounds look like hills; and the insipid flatness of our present bourgeoisie is to be measured by the altitude of its ''great intellects.''

Capital is dead labor, which, vampire-like, lives only by sucking living labor, and lives the more, the more labor it sucks.

Capital is money, capital is commodities. By virtue of it being value, it has acquired the occult ability to add value to itself. It brings forth living offspring, or, at the least, lays golden eggs.

The worker of the world has nothing to lose, but their chains, workers of the world unite.

A specter is haunting Europe -- the specter of communism.