Slavery had been around for a long time, but the Atlantic slave trade, and chattel slavery as it developed in the Americas, was something else, with some features that were uniquely horrible. It is good that people should be reminded of the part that those jolly "Elizabethan Adventurer" like Sir John Hawkins played in the establishment of this system.

The sheer scale of the slave system that developed from this source, the racial ideology that developed to underpin it, and the juxtaposition of a dehumanising slave centred economy with a highly developed and in the case of the States "progressive" and "democratic" society - these were different from anything that came before.   And they were precursors of what came after, most notably in the shape of Nazism.

The difference between traditional slavery, and the developed slave system is analogous to the difference between the endemic antisemitism that had existed, and the Holocaust. The difference between a horrible hangover from the past and a nightmare vision of a future world where these things would become normalised.

And we need to be aware that the central feature of slavery - using people as property - is not a thing of the past, it is still very much alive and constantly being reinvented and extended.