Risk is inherent in investing, and while successful investors know they need to manage risk, there is much debate as to what risk actually is. With the popularity of modern portfolio theory in recent decades, many investors associate risk with volatility. Brandes believes strongly that the true long-term risk to investors is permanent loss of capital. In our view, volatility is NOT risk, and in fact it can create opportunity for disciplined value investors.  

Source: The Intelligent Investor: A Book of Practical Counsel—Revised Edition, Benjamin Graham. Updated with New Commentary by Jason Zweig (HarperCollins, 1973, 2003)