At the outset, a person may engage in charitable works in the hope of the karmic reward of rebirth in paradise. But as the experience is repeated the person forgets about rewards and gives for the pleasure of giving, eventually advancing to the realization that even this pleasure is selfish. Warmed by the light and peace generated by giving, such a person finds life meaningless without giving selflessly and no longer even takes into consideration the pleasure to be derived from acts of giving.
Basic Buddhist Concepts