A slight change in the initial conditions will have a huge impact. This is like a trim tab on a ship. The phrase can be found on his gravestone .

Found on Wikipedia:

Trim Tab as Metaphor

The engineer Buckminster Fuller is often cited for his use of trim tabs as a metaphor for leadership and personal empowerment. In the February 1972 issue of Playboy, Fuller said:

Something hit me very hard once, thinking about what one little man could do. Think of the Queen Mary -- the whole ship goes by and then comes the rudder. And there's a tiny thing at the edge of the rudder called a trim tab.

It's a miniature rudder. Just moving the little trim tab builds a low pressure that pulls the rudder around. Takes almost no effort at all. So I said that the little individual can be a trim tab. Society thinks it's going right by you, that it's left you altogether. But if you're doing dynamic things mentally, the fact is that you can just put your foot out like that and the whole big ship of state is going to go.

So I said, call me Trim Tab.