A black snake named Mandavishya lived in a forest on the Varuna hills. He was becoming old and worried that he would not be able to snare frogs any more and that would make him weak and bring his end closer. With a plan in his head, he went to a lake and resting on its edge pretended that he had lost all interest in worldly matters.
A frog in the lake came out and asked him, "Uncle, why are you not preying for food as used you to do in the past?"
The snake said, "Listen, my son, I am very unfortunate. How can I have any fervour for food? Last night when I was on my rounds looking for food I sighted a frog. When I tried to get at him, he jumped into the middle of a group of Brahmins reciting the Vedas. I could not track him. But soon I saw something like a frog near the Brahmins and at once jumped at him and bit him. It turned out to be the thumb of a Brahmin boy. The boy died immediately."
"When his father found that I had killed his son, he cursed me, "You wicked snake, you have killed my innocent son. From now onwards you will serve as a vehicle for all frogs. Your life will be at their mercy." I have now decided to serve my sentence. That is why I am here," said the snake.
The frog ran into the lake and told every one about the snake and his offer to serve as a vehicle. Happy at the prospect, all the frogs went and met their king Jalapada and told him about the snake. "What a wonderful news," thought the king and trooped out of the lake with his ministers and subjects. The king was the first to get on to the hood of the snake, followed by his ministers. In the order of seniority and prominence, the kings’ subjects also climbed the back of the snake. Those unfortunate frogs that could not find space on the vehicle followed the snake in a procession. To entertain them, Mandavishya showed several feats he could do.
Thrilled by the experience of riding a deadly snake, Jalapada, the king of the frogs, thought that the ride had no parallel. No ride, whether on an elephant or a horse or a chariot or a palanquin, can match this experience, he thought.
On the second day, Mandavishya slowed down the pace of his haul. Noticing the change of pace, Jalapada asked the snake why he was not moving as briskly as he used to. The snake told the king of frogs that he had no food that day and being weak he was not able to carry so much load.
Jalapada, taking pity on the snake, said, "You can have the younger frogs for your food."
Thrilled at this offer, the snake said, "O king of frogs, my plight is due to the curse the Brahmin gave me. Your magnanimous concession has released me today from the curse. I am so happy."
The snake thus began eating a few frogs every day and soon became strong and healthy. As time passed he ate all the frogs including the king frog.
Brain is the real strength, by use of this you can overcome every problem.