Avoiding loss should be the primary goal of every investor. The way to avoid loss is by investing with a significant margin of safety. A margin of safety is necessary because valuation is an imprecise art, the future is unpredictable, and investors are human and make mistakes.

Margin of Safety was first published in 1991 but is now out of print. A copy of the book can sell for $2,000 or more on the reseller market these days.