The imagination muscle
Muscles get tired. This we all know. If we run up a hill or if we lift a heavy spade of dirt, our legs and arms will feel sore. Like they need a good rest. Maybe even an ice pack!
Did you know that the imagination works very like a muscle? Sometimes it feels fresh and strong, as if it could imagine anything. At other times, the imagination feels worn-out, as if it could not imagine a single strand of hair on the head of a flea.
But how long can an imagination work before it needs to stretch out in a hammock and rest?
That depends. It depends on how much exercise it has gotten in the past, and how big an imagination muscle you have built up.