How important was the slavery system to Europe?

After commending the articles in this Special Issue for opening up the study of the slavery system to new locations and positions in the value-added chain, this comment underlines that it is necessary to imagine counterfactuals to find out how important the slavery system was to Europe. It then argues that it is difficult to imagine that the Industrial Revolution depended on slavery. Yet slavery might have played an important role for the prosperity of Early Modern Europe.