But the black giant had learned that his former apprentice was making a great deal of money by practicing the trade he had taught him, and, being jealous at this, he determined to put an end to the young man's gains.
Therefore on the third day he came to the market himself as a buyer, and the moment he saw the beautiful cow with the golden horns he knew that it could be no other than his former apprentice. So he came up to the old man, and, having outbid all the other would-be purchasers, paid at once the price he had agreed on. Having done this, he caught the string in his hand, and tried to wrench it from the terrified old man, who called out, "I have not sold you the string, but the cow!" and held the string as fast as he could with both hands.
"Oh, no!" said the buyer, "I have the law and custom on my side. Whoever buys a cow, buys also the string with which it is led!" Some of the amused and astonished lookers-on said that this was quite true, therefore the old man was obliged to give up the string.
The black giant, well satisfied with his purchase, took the cow with him to his castle, and, after having put iron chains on her legs, fastened her in a cellar.
Every morning the giant gave the cow some water and hay, but he never unchained her.
One evening, however, the cow, with incessant struggles, managed to get free from the chains, and immediately opened the cellar-door with her horns and ran away.
Next morning the black giant went as usual into the cellar, carrying the hay and water for the cow; but seeing she had got free and run away, he threw the hay down, and started off at once to pursue her.
When he came within sight of her he turned himself into a wolf and ran at her with great fury; but his clever apprentice changed himself instantly from a cow into a bear, whereupon the giant turned himself from a wolf into a lion; the bear then turned into a tiger, and the lion changed into a crocodile, whereupon the tiger turned into a sparrow. Upon this the giant changed from the form of a crocodile into a hawk, and the apprentice immediately changed into a hare; on seeing which the hawk became a greyhound. Then the apprentice changed from a hare into a falcon, and the greyhound into an eagle; whereupon the apprentice changed into a fish. The giant then turned from an eagle into a mouse, and immediately the apprentice, as a cat, ran after him; then the giant turned himself into a heap of millet, and the apprentice transformed himself into a hen and chickens, which very greedily picked up all the millet, except one single seed, in which the master was, who changed himself into a squirrel; instantly, however, the apprentice became a hawk, and, pouncing on the squirrel, killed it.
In this way the apprentice beat his master, the black giant, and revenged himself for all the sufferings he had endured whilst learning the trade of witchcraft.