… is from page 233 of the 2016 second edition of Thomas Sowell’s important volume Wealth, Poverty and Politics:
In a world largely free of slavery today, it may seem hard to realize that slavery was an almost universal institution for thousands of years. Despite widespread misconceptions in the United States today that the institution of slavery was based on race, for most of the millennia in which slavery existed around the world, it was based on whoever was vulnerable to enslavement and within striking distance.