The Diderot effect is when you want things you don’t need. In 1764, the French philosopher, Denis Diderot’s daughter was set to be married but he didn’t have enough for a dowry. Diderot was the co-founder and writer of Encyclopédie, one of the most comprehensive encyclopedias of the time. Catherine the Great heard about his money troubles and offered to buy his library.

Suddenly with money to spare Diderot bought a new scarlet robe. His surroundings didn’t match his new robe, so he started to replace them with fancier versions like new rugs, mirrors, and sculptures, thus creating a spiral of consumption. This is the Diderot effect.