Wine is defined as an alcoholic drink made from the fermented juice of grapes. According to Tom Standage author of the book The History of the World in Six Glasses, only the wealthy could afford wine. Peasants drank beer or mead. As time went on, inferior wine became available to the lower classes. Roman soldiers for example, drank posca, a sour wine that was turning to vinegar and which constituted much of their wages. At a feast, guests from higher classes got the best wine, those from lower classes were given poorer quality wine. Additionally, wine was nearly always mixed with equal parts water, or with even more water if it had been fortified for shipment. Since most people drank a lot of wine, the addition of water helped maintain moderation.