Your manic partner, the market

In «The Intelligent Investor», Benjamin Graham imagines you have a partner named Mr. Market: every day he offers you a price for your share of the business. Some days he shows up euphoric and asks absurd figures; other days, depressed, he sells at a loss. The central idea: his mood is not information, it's noise. You decide when to listen to him.

From there comes his second key concept, the margin of safety: buy only when the price is clearly below the value, because you will be wrong and you need room to survive your own mistakes.

Graham separates two trades we tend to confuse: investing demands serious analysis, protection of capital and a reasonable return; anything that fails to meet that, however fine a suit it wears, is speculation.