Scenario One:

One crab starts to climb up to reach the top of the box; all of the other crabs began to tug at its bottom claw; it stumbles back to the bottom of the box; where the other crabs lie frantically scrambling along...

Scenario Two:

On its next climb to reach the top of the box, halfway up, another crab jumps onto its back; next thing it knew, they were both abruptly falling back to the bottom of the box; frustrated that its halfway climb's hard work was interrupted...

Scenario Three:

At its last climb to reach the top of the box, through the leading crab's effort, it finally reached the top of the box; it paused and thought to itself "that climb was different" -- why?"; from the top of the box, it looked back and saw that the other crabs were standing upon each other's shoulders; in kind, the leader crab extended to reach down to lend a helping claw.

Sageview Blogger 2008