Lost, Season 1

John Locke:
That's a moth cocoon. It's ironic, butterflies get all the attention; but moths -- they spin silk, they're stronger, they're faster.

Charlie Pace:
That's wonderful, but...

John Locke:
You see this little hole? This moth's just about to emerge. It's in there right now, struggling. It's digging its way through the thick hide of the cocoon. Now, I could help it, take my knife, gently widen the opening, and the moth would be free. But it would be too weak to survive. The struggle is nature's way of strengthening it. Now this is the second time you've asked me for your drugs back. Ask me again and it's yours.