Kohle (coal)

"Der Schornstein muss rauchen" — the chimney has to smoke — was an 18th-century German idiom reminding that money is needed to keep the house warm. There are several German terms for money related to combustible materials. "Kohle" is one of those most commonly used, along with "Asche," ashes. Coal was a scarce commodity during war times and became an informal means of payment.