Adam Smith is the Enlightenment thinker most closely associated with the concept of the invisible hand. The phrase describes how people pursuing their own interests can sometimes unintentionally contribute to wider social benefits through exchange and market activity.
Smith used the expression in The Wealth of Nations, published in 1776, while discussing why a merchant might prefer to invest capital domestically rather than abroad. He argued that this personal choice could increase domestic production and employment, even though promoting the public interest was not the merchant's aim.
A common oversimplification is to treat the invisible hand as a claim that markets always produce perfect outcomes. Smith did not present it as an absolute law, and he also used the phrase in The Theory of Moral Sentiments in 1759. The modern broad interpretation of the idea became especially influential through later economists, including Paul Samuelson.