Investment managers must always be reasonable and prudent people, sort of like the way we tend to picture accountants and clergymen. Prudence, in turn, tends to imply carefully following the consensus opinions of the time. However, in the investment business, prudence means a lot more. It often means looking ahead and investing in advance of the movements in conventional wisdom, and it means recognizing that what seems secured today may not be secure tomorrow. Similarly, it means making some investments that defy the common judgment of the time. Since no investor has a perfectly clear crystal ball, good investing amounts to careful analysis of the past, present, and probable future—with an important weight given to the future.