Seth Klarman’s extraordinary and mysterious book Margin of Safety, Risk Averse Investing Strategies for the Thoughtful Investor has sold for $700 for used varieties with newer copies going for $2,500 to $4,000. His foremost investing premise is risk mitigation. He writes,

Investors must recognize that the early success of an innovation is not a reliable indicator of its ultimate merit… At the time of issuance a new type of security will appear to add value in the same way that a new consumer product does. There is something—lower risk, higher return, greater liquidity, an imbedded put or call option to the holder or issuer, or some other wrinkle—that makes it appear superior (new and improved, if you will) to anything that came before. Although the benefits are apparent from the start, it takes longer for problems to surface. Neither cash-hungry issuers nor greedy investors necessarily analyze the performance of each financial-market innovation under every conceivable economic scenario. What appears to be new and improved today may prove to be flawed or even fallacious tomorrow.