A turtle was happily swimming along a river when a scorpion hailed it from the shore. "Dear friend turtle!" called the scorpion. "Please let me climb upon your back and swim me to the other side of the river!"
"No," replied the turtle, "for if I do, you shall sting me, and I shall die."
"Nonsense!" replied the scorpion. "If I kill you in the middle of the river, you shall sink, and I shall drown and die with you."
The turtle thought this over, and saw the truth of the scorpion's statement. He let it upon his back and began swimming towards the other side of the river. Halfway across, he felt a sharp pain in the back of his neck.
"Why have you stung me?!" cried the turtle as his body began to stiffen. "Now you shall die as well!"
"Because it is in my nature," replied the scorpion as the turtle sank beneath the waters.