>[B]oth rent and profit amount to money left over once costs are paid for… profit is vulnerable to market competition, rent is not… **Rent flows from privileged access to things in fixed supply**, like fertile soil or land containing fossil fuels; you cannot produce more of these resources, however much money you might invest in them. Profit, in contrast, flows into the pockets of entrepreneurial people who have invested in things that would not have otherwise existed… It is this fact – that these commodities were invented and created and so can be invented and created again but better by someone else – that renders profit vulnerable to competition.