Suppose you were to come upon someone in the woods working feverishly to saw down a tree.
"What are you doing?" you ask.
"Can't you see?" comes the impatient reply. "I'm sawing down this tree."
"You look exhausted!" you exclaim. "How long have you been at it?"
"Over five hours," he returns, "and I'm beat! This is hard work."
'Well, why don't you take a break for a few minutes and sharpen that saw?" you inquire. "I'm sure it would go a lot faster."
"I don't have time to sharpen the saw," the man says emphatically. "I'm too busy sawing!"