... interestrate.Assuming that we care about the quantity of goods andservices that we can buy with money, rather than moneyitself, it would seem reasonable to suppose that it is the realinterest ... world were to lower theirreal rate of interest, say 1 per cent. below its ordinarylevel, and keep it so for some years, then the prices ofall commodities would rise and rise without any limitwhatever; ... position of the investment curve in figure 2 will dependon factors related to the productivity of capital, or in otherwords, how profitable investment in capital is. Theproductivity of capital...