Socialism's singular idea: that mankind would truly thrive only if property were shared by all.
The first seeds of socialism are planted on the banks of Indiana's Wabash River, a utopian community designed by a social reformer who later inspired Karl Marx.
As Vladimir Lenin's brutal communist revolution transforms Russia, socialism stalls in the United States.
Mao takes over China and socialism peaks worldwide with 60 percent of mankind living under some form of it.
Poorer countries embrace socialism, while Margaret Thatcher tamps down British socialists.
The USSR implodes, China reforms and other countries embrace capitalism.
Socialism makes a surprising comeback across the world.