To grasp "what economics is actually arguing about"
Follow the "market vs. government" main line: Adam Smith said the market has an "invisible hand" and government had best manage little; the Great Depression led Keynes to rebut that the market fails and government must step in; Hayek and Friedman struck back that government intervention brings greater harm. You will find that two centuries of economic debate has largely unfolded around this one question — and every economic crisis tips the scales anew.