The intelligent investor is a realist who sells to optimists and buys from pessimists.

This line is commonly presented as investment advice about how market sentiment affects prices. It frames investing as taking the opposite side of emotional extremes—selling when enthusiasm inflates valuations and buying when fear depresses them.

A disciplined investor should focus on underlying value rather than crowd mood, using optimism and pessimism as signals of potential mispricing and acting contrarily when prices detach from fundamentals.