First; A group of citizens overpowered another group of citizens and forced them to agree with them (by force) that a particular action was immoral.

Does the actions of the stronger group dictate morailty or immorality of the lesser group? Yes, the stronger group set the norm of what was socialy acceptable. Thus today we see slavery as immoral.

1860- A couple sells themselves into slavery for a tract of land.

2007- A couple goes deep in debt for a tract of land.

Immoral ? No. Doesn't matter how you make your payments you still have to pay for your land.

Not bad for a couple of "ole" hayseeds? Eh?