William Bramley/The Gods of Eden/21/215/3

With more and more notes outstanding, an increasing number of notes will start coming in for redemption. Soon the farmer will see that his true wealth, which is his supply of chickens, is becoming rapidly depleted even though only a small portion of his outstanding notes have come back. To preserve his chickens, he must decrease the value of his notes by declaring that the outstanding notes are now only good for half of what they say. This is called devaluation.