I think a lot about what I sometimes call “abstract commodity space.” Sometimes you want to buy nickel or aluminum or coffee or cocoa to make batteries or beer cans or cappuccino or chocolate bars, so you go to some supplier and negotiate a contract for the delivery of a useful amount of a particular grade of the commodity to your factory. Sometimes, though, you want to bet on the price of nickel or aluminum or coffee or cocoa, to hedge some risk to your business or just as a speculative bet. ...