Leisure has often been defined as a quality of experience or as free time. Free time is time spent away from business, work, job hunting, domestic chores, and education, as well as necessary activities such as eating and sleeping. Leisure as an experience usually emphasizes dimensions of perceived freedom and choice. It is done for "its own sake", for the quality of experience and involvement. Other classic definitions include Thorstein Veblen's (1899) of "nonproductive consumption of time." Free time is not easy to define due to the multiplicity of approaches used to determine its essence. Different disciplines have definitions reflecting their common issues: for example, sociology on social forces and contexts and psychology as mental and emotional states and conditions. From a research perspective, these approaches have an advantage of being quantifiable and comparable over time and place.