Crusoe engages in the activities just described, not for their own sake, but in order to generate a good for his later consumption. Such activities may be referred to collectively as production. Activities pursued primarily for their own sake—that is, because they provide immediate satisfaction to the acting human being—may be called leisure. For instance, Crusoe may later decide that he derives so much satisfaction from this activity that he would like to build additional tree houses as a hobby, even though he will probably never make use of them all. The creation of tree houses will then become a leisure activity, pursued in large part for its consumption value (i. e., as an end in itself), yet structured similarly to the productive activity we have been examining and likewise subject to praxeological analysis and principles.