It’s no surprise that financial crises – like intercourse, pro sports, and agriculture – run in alternating cycles of boom and bust. Classical economic theory suggests that such cyclicality can be overcome through innovations in resource use, factor productivity, and leverage. Classical history suggests otherwise. In the following rant, celebrity economist Jeff Sachs tackles the two-headed plague of stagflation — part stagnant economic growth, part inflation — and offers the 1970s as an illustrative case study in how to keep a resource-hungry, debt-ridden, war-wearied hegemon from spinning its economic wheels…