The French philosopher Denis Diderot lived nearly his entire life in poverty, but that all changed one day in 1765. Diderot’s daughter was about to be married and he could not afford to pay for the wedding. Despite his lack of wealth, Diderot was well known for his role as the co-founder and writer of Encyclopédie, one of the most comprehensive encyclopedias of the time. When Catherine the Great, the Empress of Russia, heard of Diderot’s financial troubles, her heart went out to him. She was a book lover and greatly enjoyed his encyclopedia. She offered to buy Diderot’s personal library for £1,000 —more than $150,000 today.* Suddenly, Diderot had money to spare. With his new wealth, he not only paid for the wedding but also acquired a scarlet robe for himself. Diderot’s scarlet robe was beautiful. So beautiful, in fact, that he immediately noticed how out of place it seemed when surrounded by his more common possessions. He wrote that there was “no more coordination, no more unity, no more beauty” between his elegant robe and the rest of his stuff. Diderot soon felt the urge to upgrade his possessions. He replaced his rug with one from Damascus. He decorated his home with expensive sculptures. He bought a mirror to place above the mantel, and a better kitchen table. He tossed aside his old straw chair for a leather one. Like falling dominoes, one purchase led to the next. Diderot’s behavior is not uncommon. In fact, the tendency for one purchase to lead to another one has a name: the Diderot Effect. The Diderot Effect states that obtaining a new possession often creates a spiral of consumption that leads to additional purchases.