The demesne was an important source of income for the lord, as it provided him with a steady stream of food, rent, and other goods. It was also a symbol of the lord's power and authority, as it demonstrated his control over the land and the people who worked on it.
The size of a demesne could vary significantly depending on the wealth and power of the lord. Some demesnes were only a few acres in size, while others could be hundreds or even thousands of acres. The demesne was often the most valuable part of the manor, and it was often passed down from generation to generation as part of the lord's inheritance.
Demesnes began to decline in size and importance in the late Middle Ages, as lords increasingly granted land to their knights and other vassals in exchange for military service. This process, known as enfeoffment, led to the rise of the feudal system, in which land was held by vassals who owed loyalty and service to their lord. By the end of the Middle Ages, the demesne had largely disappeared, as most lords had granted away most of their land to their vassals.