First let me confess that Hinduism is a religion of the Brahmins, by the Brahmins, for the Brahmins. In spite of this fatal flaw, for people who can overlook this unforgivable bias, there are such quintessential moralistic stories that transcend bias and serve as fundamental moral beacons and answers to what a decent moral human being should do. Even under adverse circumstances, to behave ethically at the cost of the expediency based, pragmatic and self-serving principle of survival is called "Dharma". The weakness and strength of humanity is the ability to reflect on one's actions both encumbered and unencumbered by any considerations of principle, morality ore ethics. This is what Plato called living an examined life.
Let me get to the story, which is the critical redeeming myth from approximately 1500 BCE. After the Pandavas had won an incontrovertible victory over the Kauravas, which was well deserved as a victory of good over evil in spite of some unorthodoxies and manipulation of truth and good, they felt it incumbent upon themselves to expiate their sins by doing public good. The greatest importance in the Hindu religion for good is given to feeding of the hungry. They set up a communal kitchen where none was refused food. After the fires of the kitchen hearth had become embers and ashes, the assigned cooks noticed a strange creature was rolling in the ashes. This anomalous animal had half its body which was golden and it passionately anointed itself with the ashes of the fires that cooked the greatest giveaway of food in the then known history of mankind. After repeatedly rolling in the ashes without any effect, the disappointed mongoose snorted with frustration and unconcealed disgust. A curious cook then questioned the mongoose what it was trying to accomplish? The divine mongoose with gift of speech, replied that many eons ago half his body had turned golden by rolling in the ashes of a fire of sacrifice and it was just following the greedy and self-serving penchant of all creation to turn the rest of its body to the same desirable and golden hue. The curious cook asked what were the circumstances that turned its half body golden.
The mongoose related the story. There was once upon a time a Brahmin family that was so poor that the Bhiksha or begging had not given them any food for days. Fortunately after many days of starvation, the man who was head of the family managed to collect enough flour to make four chappatis. He ran home to allow his wife to cook those four chappatis to assuage their longstanding hunger. When she had finished making the four chappatis, one each for the man, his wife, his son and the pregnant daughter-in-law, a mendicant came to their door and asked for food. The Hindu Dharma requires that a guest is like a god and no mendicant be turned away from the door without some offering. That is what makes Karna so renowned in the Mahabharata and forms the basis of Pashtunwali the ethical code of the Afghan tribes.
So the elderly starved Brahmin told his wife to offer his share of one roti to the beggar. She did that but the beggar asked for more because his hunger was not fulfilled. The wife then offered her share of one roti to the beggar. She claimed that she was the Ardhangini of her husband and bore equal responsibility of his Dharma to feed any mendicant. The starved mendicant said he was still hungry and the son gave his share of his one roti to him in spite of his father's protest. The son said, Ò this is my family and its reputation, morality and proper behavior are my legitimate concern, greater than my life or salvation, but consistent with my principles". The mendicant's insatiable hunger was not fulfilled and he asked if there was more food to give. The pregnant daughter-in- aw then suggested that she should give her share of the last remaining roti. All the family members protested and objected on the basis, that she was pregnant and had been starved and should not jeopardize the life of the unborn fetus. The dutiful daughter-in-law replied, Ò No one is born or even conceived without obligation. If this child whatever its sex, is part of this family, then it comes to this earth with its own obligations. It does not have the free will to decide, but as its mother and consistent with the ethics of my beliefs, it is my rightful choice to make this sacrifice on its behalf consistent with my Dharma and its. No living sentient creature is exempt from Dharma even before birth. The family agreed and the last of the four rotis was given to the mendicant, who was satisfied.
The mongoose said to the Pandava cook, "By chance, I rolled into the ashes of the Brahmin's hearth and half my body turned golden, Since then for eons, I have rolled in myriad hearths where people proclaimed great sacrifices were made with purely altruistic motives, in the hope of making my whole body golden, but my reward has been disappointment and frustration. Is there no human being that is altruistic enough to fulfill my dream and wish by matching this ancient sacrifice?"