"However, there is something they value more than a man's life: a trowel."

"Why a trowel?"

"If a bricklayer drops his trowel, he can do no more work until a new one is brought up. For months he cannot earn the food that he eats, so he must go into debt. The loss of a trowel is cause for much wailing. But if a man falls, and his trowel remains, men are secretly relieved. The next one to drop his trowel can pick up the extra one and continue working, without incurring debt."

Hillalum was appalled, and for a frantic moment he tried to count how many picks the miners had brought. Then he realized. "That cannot be true. Why not have spare trowels brought up? Their weight would be nothing against all the bricks that go up there. And surely the loss of a man means a serious delay, unless they have an extra man at the top who is skilled at bricklaying. Without such a man, they must wait for another one to climb from the bottom."

All the pullers roared with laughter. "We cannot fool this one," Lugatum said with much amusement.

Ted Chiang, Tower of Babylon