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).
Understanding the relationship between climate and ecosystems is crucial to preventing undesired changes to our environment, such as desertification and the loss of species. However, the multi-component and multi-scale nature of ecosystems makes them difficult to easily understand.
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