The Asymmetric Ledger of Entropy There's one key question in this quarter's letter that’s relevant for every individual, investor, company, country and civilization: what did you choose to build and protect, and did you understand what it cost? There's also one key idea that competitively advantages all who understand it and disadvantages all who don't, and equally applies to business and biology, technology and treaties: entropy. Consider what it costs to build a skyscraper, car or jet.