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).
Rice, maize, soybeans and wheat are the main source of nutrients for over 2 billion people living in poor countries. But with climate change and the rising amount of CO2 in the air we breathe, their already low nutrient value compared to meat, for instance, is set to decrease.
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