Debt: the First 5000 Years by David Graeber

It's really good, and really thought-provoking. I can only read about a chapter a day because each one gives me a lot to think about.

So far the thing that's resonating most with me is the distinction between intangible debt that mostly serves to create social relationships and obligations, and monetary debt which can be purely transaction. The whole "gig economy" is turning activities that used to be the former, like giving your friend a ride, into the latter and increasing social alienation as a result.