The Black Death was a bubonic plague that wiped out about one-third of the population in Europe in the 14th century. This event decreased one-third of the population in only a few short years. This event clearly shows the results and impact that it had on the supply and demand of labor in the market. With this smaller supply of population or workers, the marginal product of the labor rose. This effect can be looked at as diminishing marginal product working in reverse. The Black Death event caused wages to rise. Because land and labor were used together in production, a smaller supply of workers also affected the market for land, the other major factor of production in medieval Europe. With fewer workers available to farm the land, additional units of land produced less additional output. This basically caused the marginal product of land to fall. This event caused the rents to lower. During this period, wages approximately doubled, and rents declined 50 percent or more. This major event led to economic prosperity for the peasant classes and reduced incomes for the landed classes. (9780324832945, Principles of Economics, 4e, N. Gregory Mankiw - © Cengage Learning) If we look at this closely, before this event happened, likely, the landed class was doing well financially because their land was very valuable and there were an abundance of workers so they could in turn pay cheap labor to them. As the labor diminished, the wages of the workers increased, causing the lower class to be in a better financial position. Since there were fewer laborers, less land was being produced causing the value of the land to decrease, leaving fewer profits for the landowners.