Graeber / Wengrow, discussing surplus (128)
"As philosophers realized long ago, this is a concept that poses fundamental questions about what it means to be human. One of the things that sets us apart from non-human animals is that animals produce only and exactly what they need; humans invariably produce more"
Also, "[r]uling classes are simply those who have organized society in such a way that they can extract the lion's share of that surplus for themselves"