DURHAM, N.C. -- It's always been a mystery to me, how someone not long for this world could care so much about it. Even now -- his voice almost gone -- Chris Rosati still has a lot to say about how to make the world a better place. We've been following his journey as he lives with ALS. We've watched him give away donuts and honor kids for their random acts of kindness. His latest revelation is about the butterfly effect.

The butterfly effect is this idea that a single butterfly flapping its wings on one side of the globe can, in theory, start a hurricane on the other. It's a physics concept, but Rosati wondered if it could be applied to kindness as well.

"An act of kindness, how far could it go?" he wondered.

A few months ago he decided to test the theory at a diner in his hometown of Durham, North Carolina. He saw two girls at the table next to his and gave them each $50 with one very simple instruction -- do something kind.

Rosati says he left the diner and forgot all about it until he got an email. It included pictures from a village in Africa with people holding signs that read, "Thanks a lot for spreading kindness -- Chris Rosati."

"It was the butterfly effect," said Rosati.

Cate Cameron, right, and her sister Anna, left CBS News

The two girls responsible were 13-year-old Cate Cameron and her 10-year-old sister Anna. They say they couldn't believe it when a stranger gave them each $50 dollars.

"That makes you want to do something good with that money," said Anna.

The girls say they already knew about this village in Sierra Leone where their dad had worked in the Peace Corps. They knew the people there had been working hard to fight Ebola, so the girls paid for a feast to help them celebrate being Ebola-free. They say it felt great to help.

Children in Sierra Leone hold signs thanking Chris for spreading kindness STEVE CAMERON

"It inspired me," said Anna.

"I would definitely encourage other people to do it," added Cate.

I asked Rosati what he'll do now that he's proven the butterfly effect.

"Oh man," he said. "You get a whole lot of butterflies to flap their wings."

To that end, Rosati, who's already done so much for North Carolina, launched his latest campaign last month. He told screaming fans his plan to give out hundreds of little butterfly grants -- $50 each -- to any kid who wants to start changing the world.

America, get ready for a hurricane.

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