Sparta organized its society around military strength and discipline. Spartan boys began military training at age 7 and remained in the military until age 60. All males were required to serve in the army and physical fitness was highly valued. Spartan women had more rights than other Greek women, such as owning property and running households, due to the long-term military service of men. Sparta was ruled by two kings and had many slaves called Helots who performed most of the agricultural and domestic work. In contrast, Athens valued education, clear thinking, the arts, and physical fitness. Athenian democracy allowed only brief military service for men from ages 18 to 20.