I've never understood that little nuggest of wisdom myself. Seeing as pretty much every successful civilisation in history has been built on the backs of slaves, you'd think there'd be quite a list of people hard work had killed. In fact, if you put hard work in front of a jury I'm pretty sure it'd get life in prison (Or, if the judge was feeling particularly cruel, maybe even 3 years! With bail, of course)
Please forgive the lack of furriness.