The Merchant's Scales

A merchant weighed his goods each morning before selling.

"Wasteful," another merchant said. "You know roughly what you have."

"I know exactly what I have. And I know if something has been taken. And I know if my supplies are damp, because damp goods weigh more. And I know if my flour has weevils, because infested sacks weigh less."

"All that from a scale?"

"All that from paying attention."