Trade involves the transfer of goods or services from one person or entity to another, often in exchange for money. A system or network that allows trade is called a market.
The product of mental labor — science — always stands far below its value, because the labor-time necessary to reproduce it has no relation at all to the labor-time required for its original production.
Karl Marx Addenda, "Relative and Absolute Surplus Value" in Economic Manuscripts (1861–63).
Palaeoceanography studies the history of the oceans, including their chemistry, temperature and salinity. This information enables conclusions to be drawn regarding configuration and intensity of ocean circulation, which in turn is the main amplifier of climate change.