This collapse is likely to be profitable for one fund manager who has for decades made a point of sticking to his own fundamental notions of value: the American billionaire Warren Buffett. His great mentor was Benjamin Graham, an influential American investor whose key insight was that, on the stock market, there is a deceptively simple duality. Graham called this the Class One versus the Class Two truth. A Class One Truth is a sober assessment of a company’s objective worth at a point in time: the figure you get after you add up the value of its property, cash and other assets, then subtract its debts. A Class Two Truth, by contrast, is based on external factors such as emotion, fashion and herd instinct: it is ‘true’ only for as long as we continue to believe in it, just as a designer handbag is only worth £5,000 if people think so. When there is a discrepancy between the two types of truth on the stock markets, there is a chance to make money.