It is impossible to be a successful equity investor without the willingness to accept some amount of market risk when conditions appear frightening. If anything should be clear from the bubbles of recent years, the greatest risks are not when prices are depressed, the economy is weak, and investors are frightened, but rather when prices are elevated and an unendingly positive outlook for technology, or housing, or global growth, or private equity, or emerging markets, or commodities seems all but certain.