 If someone performs an act entirely from altruistic motives—if, that is, self-interested motives are entirely absent—we can describe her act as a case of “pure” altruism. We should be careful to distinguish purely altruistic behavior from self-sacrificing behavior: the former involves no gain for oneself, whereas the latter involves some loss. If someone has a theater ticket that he cannot use because he is ill, and he calls the box office so that the ticket can be used by someone else, that is a case of pure altruism, but it involves no sacrifice.