Once, a man was selling spears and shields. He highly boasted of his shields and said, “Look at the best shields! See the design and the quality! And look at the shape! No spear on the earth can pierce them! It is the surest protection for your body! Buy it to be a respected warrior!” The man kept his shields down and raised one of his spears and shouted, “This is the sharpest spear you have ever seen. It is a spear of death!
Any shield, no matter how hard it might be, can be penetrated by this spear at a single stroke!” Everyone started praising the spears and shields. But one of the by-standers came ahead and asked, “Tell me, what will happen if I use your spear to strike your shield.” The seller rolled his eyeballs, thought for a moment, but couldn’t find any good answer. Instead, he went away.