If a person wants to make a living in this game, he must believe in himself and his judgment.
Because when I make a mistake, there is only one thing that can make me believe that I made a mistake, that is, losing money. Only when I make money, I am right, and this is speculation.
———"Reminiscences of a Stock Operator" Chapter 3: Returning to Wall Street and Suffering a Heavy Blow: Adapt to the Stock Market, Not Let the Stock Market Adapt to You