Bread is a food consisting of flour or meal that is moistened, kneaded into dough, and often fermented using yeast, and it has been a major sustenance since prehistoric times. With the right ingredients, it can be a source of complex carbohydrates and B vitamins (add whole wheat, and you increase its nutritional value). Through synecdoche, its name rose to refer to any source of food or sustenance. Reference to a path to sustenance followed in the 18th century. "I was under no necessity of seeking my bread," recounts Daniel Defoe's Robinson Crusoe. Dough had already been used to refer to money in 19th-century slang and, in a natural extension, bread was served with the same meaning in the jazz and beat slang of the mid-20th century ("Dean just raced in society, eager for bread and love," writes beatnik Jack Kerouac).