The Butterfly Effect

I watched the butterfly flutter up into the canopy of the tree. 

As it flew out of view, a leaf fell. Followed by another, and another until there was a flurry of them, falling like rustling snow. 

No, I thought. Surely the flapping of a butterfly's wing couldn't have caused all that?

Then it struck me that the strong gust of wind was a more likely culprit.