Communism: A State-enforced slavery

Everyone has heard or read the following sentence:

From each according to his ability, to each according to his need."

It's one of the best descriptions of communism I have heard, and I'm sure many agree. Some think it's "a beautiful thought", and then add, "but humans are too selfish to be able to work according to it". But is that why it doesn't work? If humans were more giving and loving would it then work? Would it work and would it make us happy?

In short: No. Slaves work according to their ability (or else face punishment or even death from their master). They receive just what they need - minimum food and clothes and a place to sleep. Karl Marx was in fact describing the lives of slaves throughout human history. Slavery is evil. Communism is evil along with all its socialistic roots.