Theravada and Mahayana Buddhists differ in their perspective on the ultimate purpose of life and the way in which it can be attained. Theravada Buddhists strive to become arhats, or perfected saints who have attained enlightenment and nirvana. This is considered to only be possible for monks and nuns, who devote their entire lives to the task. The best outcome the laity can hope for is to be reborn in the monastic life.