The following is an annotated version of the fairy tale. I recommend reading the entire story before exploring the annotations, especially if you have not read the tale recently.
THERE was a certain Brahmin whose wife died leaving him one little son. For some time the two lived happily together, but at last the Brahmin married for a second time, and the woman, who had a daughter of her own, was very unkind to her little stepson.
Each day the two children went out together to attend to the cattle, and at night they returned home to eat their food. But the cakes made by the Brahmin's wife for her stepson were of ashes, with just a little flour mixed in to give them the appearance of food, that the Brahmin might not notice; and the child at in silence, for he was afraid to complain, yet, when he was alone in the forest he wept from hunger, and a black cow, one of the herd, saw this, and asked him what was the matter.
The boy told her everything, and presently she beat her hoofs upon the ground. As she did so, sweets of all kinds appeared, which the child ate greedily, and shared with his little sister, warning her the while not to mention what the black cow had done, lest the stepmother should be angry.
The stepmother meanwhile wondered to see how well the boy looked, and she resolved to keep watch, for she suspected that he drank the milk while tending her cows; so she told her little daughter to keep a good look-out on all his doings, and to let her know. At last the girl confessed that they ate sweets every day, and the black cow provided the feast.
That day when the Brahmin came home his wife begged him to sell the black cow, and said she would neither sleep nor eat until this was done.
The poor boy was sad indeed when he heard this, and went at once to his favourite, where, throwing himself on the black cow's neck, he wept bitterly.
"Do not weep, my child, but get up on my back, and I will carry you to a place of safety where we can still be together."
So they escaped to a forest, and there lived in peace and security for many days.
Now, in the forest was a hole, which led to the home of the Great Snake, which, together with a bull, holds up the universe. Into this hope the black cow poured five seers of milk daily to feed the snake. This pleased the snake so much that he said one day: "I must go up into the world and see for myself the creature who is so good to me and who sends me such good milk to drink."
When he came he saw the black cow grazing with the boy beside her.
The cow asked no favours for herself, but when the snake asked what she would like, she said she would like her son, as she called the Brahmin's son, to be clothed in gold from head to foot, and that all his body might shine as gold.
This wish the snake readily granted, but both cow and boy afterwards regretted their request, for they feared robbers.
One day as the boy had his bath by the river, and combed his long locks of pure gold, some of his golden hair fell into the water, and was swallowed by a fish. This fish was caught by a fisherman, and taken for sale to the King's Palace. When they cut it open all present admired the lovely golden hair, and when the Princess saw it, she said she would never be happy again until she met the owner. The fisherman was asked where he caught the fish, and people were dispatched in all directions in boats to search both far and wide.
At last a man in one of the boats espied in the distance a beautiful shining object taking a bath by the river-side. Little by little the boat came closer and closer, until it was alongside; then the man called out and asked the bather to come a little nearer. At first the Brahmin's son would not listen, but after a time he came up to the boat, when, to his surprise, he was at once seized, tied up, and carried away.
Arrived at the King's Palace he met the Princess, who was very beautiful; and when he saw her he forgot everything else, and thought only of her.
After a short time they were married, and spent many happy days together; but some one chanced to offer them a sweetmeat made of curds, such as the black cow often gave her boy, and in a frenzy of remorse, the Brahmin's son remembered his faithful friend and hastened to the place in the distant forest where he had last seen her. Arrived there he found only a few bones of dead cattle strewn about.
He was heart-broken at the sight, and gathered all the bones together into a funeral pyre, upon which he declared he would lay down his own life; but just as he was about to do this who should appear but his old friend, the black cow.
They were overjoyed to see each other, and she told him she had only kept the bones there to test his affection; but now that she was satisfied that he had not forgotten her, the meeting was full of happiness and joy, so they held a great feast for many days and then went their separate ways as before.
Dracott, Alice Elizabeth Dracott. Simla Village Tales, or Folk Tales from the Himalayas. London: John Murray, 1906.