If there is a higher duty than social mores, it is not duty per se. but compassion. For it is compassion that inspires us to help others regardless of the boundaries of culture, race, nation or species. The virtue performed by compassion is thus spontaneous and genuine rather than forced, premeditated or dutiful. Again if we consider the decades of tireless service to humanity as lived by the Buddha and the other arahants, how can we say they did not perform their 'duty' to the world?