On May 5th, 1818, Karl Marx, hero of the international proletatiat, was born. His revolution of Socialist theory reverberates throughout the world carries on to this day, in increasing magnitude. Every passing day, he is vindicated. His analysis of Capitalism, development of the theory of Scientific Socialism, and advancements on dialectics to become Dialectical Materialism, have all played a key role in the past century, and have remained ever-more relevant throughout.
He didn't always rock his famous beard, when he was younger he was clean shaven!
Some significant works:
Economic & Philosophic Manuscripts of 1844
The Eighteenth Brumaire of Louis Bonaparte
Critique of the Gotha Programme
Manifesto of the Communist Party (along with Engels)
And, of course, Capital Vol I-III
Interested in Marxism-Leninism, but don't know where to start? Check out my "Read Theory, Darn it!" introductory reading list!
Also, the surplus in nearly all the periods of ancient Rome, was still largely an agrarian surplus, extracted either from slaves, or from feudal workers / colonates in the territories outside the city.
The city / empire survived not by its own products and a commodity-producing economy, but by feeding an agrarian surplus off its many colonies.