The fundamental relation of capital to income has been much discussed by economists, the former being likened to a tree on the land, the latter to the fruit or the crop; the former depicted as a reservoir supplied from springs, the latter as an outlet or stream to be measured by its flow during a period of time…Here we have the essential matter; not a gain accruing to capital; not a growth or increment of value to the investment: but a gain, a profit, something of exchangeable value proceeding from property, severed from capital.