Guest ifor states:

>>>
The slave trade from Africa to the Americas was on a gigantic scale involving many millions of captives . Surely it was the scale of the barbarity which distinguished it from other slave societies. <<

yes and.. in Rome a slave could purchase his freedom and earn the wages to do it. Slavery in Rome was awful for certain classes of slaves but for some it was more like indentured servitude. Slavery in the Bible too gets a lot of pointing at but you could not kill a slave and there were other societal constraints on Slavery there as well. Slaves in Judea could also purchase their freedom. That doesn't sound much like what happened in the Atlantic Slave Trade now does it?