Exchange from the perspective of commodity 'exchangeability' and demand by consumers is a cross-culturally comparable (and often archaeologically detectable) means of assessing value, but this approach depends on the goods actually circulating. Others have observed that some inalienable objects (heirlooms) are valued precisely because they do not circulate, and the ability of an object to "accumulate history" is another means of establishing value albeit a measure that is difficult to establish archaeologically.