Way back when there was a caveman named Og. He was a perfectly normal sort of caveman - he'd go out and hunt all day while his wife, Ogette, kept the cave clean and gathered vegetables and took care of the kids. One day, Og went out to hunt the sabertooth tiger. He had a pretty successful day - didn't get eaten, which was always a plus - but when he came back with the spoils of his hunt he discovered a large boulder had fallen off the mountain and was blocking Ogette and their two kids, Ogling and Betty, inside the cave. Og tried with all of his might to move the boulder, able all the while to hear Ogette calling for help, but it wouldn't budge.
Then, Og had a thought (something of a rare occurrence for him). Og's neighbor a few caves down, name of Lever, was a clever guy. He spoke in full sentences and everything. Lever was really good, particularly, at moving heavy stuff around. So Og called to Ogette and Ogling and Betty that he was going to get help, and rushed off to find Lever.
Og and Lever came back, and Lever considered the situation, then nodded, quite sure he knew what to do. Hunting in the forest he found a big tree branch and a large rock, wedged the branch under the boulder and heaved. And heaved. And heaved some more. But the boulder didn't move. But Lever was not to be deterred. Heading off into the forest again he found a bigger tree branch and a larger rock, came back, wedged the bigger branch under the boulder and once more he heaved. And heaved. And he and Og heaved together. And still the boulder didn't move.
Og's other neighbors were starting to gather around at this point, and one at the back, name of Nate, came forward and asked what was going on. Then, when Og explained that Ogette and Ogling and Betty were trapped inside the cave, and that he and Lever had tried everything they could think of to move the boulder, Nate nodded wisely. "Oh, ok, I see," he said, and then stepped forward and simply pushed the boulder out of the way as though it was the easiest thing in the world. Ogette and Ogling and Betty were saved, and there was much rejoicing.
And the moral of the story is, better Nate than Lever.