Marks, co-founder of Oaktree Capital, distills decades of his famous memos into a philosophy of risk, contrarianism, and second-level thinking. First-level thinking says it's a good company, let's buy. Second-level thinking says everyone thinks it's great, so it's overpriced, let's sell. Buffett opens Marks's memos before anything else on his desk. That should tell you something.

The case for it, the case against, and the rest of the canon open with Pro.