What, then, is value? Marx considers that most errors on this subject have arisen from confusing value with utility on the one hand or with price on the other, and he regards his discrimination of value from these two ideas as his most important contribution to political economy. He takes his start from the distinction current since the days of Adam Smith between value in use and value in exchange, and of course agrees with Smith in making the value of a commodity in exchange to be independent of its value in use. Water had great value in use and none in exchange, and diamonds had great value in exchange and little in use. Value in use is therefore not value strictly so called, it is utility; but strictly speaking value in exchange, according to Marx, is not value either, but only the form under which in our state of society value manifests itself. There was no exchange in primitive society when every family produced things to supply its own wants, and there would be no exchange in a communism, for in an exchange the transacting parties stand to one another equally as private proprietors of the goods they barter. And where there was no exchange there could of course be no exchange value. No doubt there was value for all that in primitive times, and there would be value under a communism, though it would manifest itself in a different form. But as we live in an exchanging society, where everything is made for the purpose of being exchanged, it is in exchange alone that we have any experience of value, and it is only from an examination of the phenomena of exchange that we can learn its nature.