We have become accustomed to some scents, while others surprise us out of the blue. Through the direct connection that scents take to the brain, they can quickly evoke memories. Comforting nostalgia or spontaneous disgust—this is not decided by the slow mind, but rather by the quick emotion. The writer Marcel Proust experienced sudden feelings of happiness at the smell of Madeleine cakes, which reminded him of carefree childhood days, while most French people probably ignore Madeleines. The same smell affects different people in very different ways, depending on what they associate with it. While some people happily refuel their cars because the smell of gasoline evokes images of summer holiday trips, Vietnam veterans describe the opposite: They had to douse and burn corpses with gasoline during the war. To this day, they cannot refuel without feeling nauseous and a kind of spontaneous panic.