Salt

“I really don't know why it is that all of us are so committed to the sea, except I think it's because in addition to the fact that the sea changes, and the light changes, and ships change, it's because we all came from the sea. And it is an interesting biological fact that all of us have in our veins the exact same percentage of salt in our blood that exists in the ocean, and, therefore, we have salt in our blood, in our sweat, in our tears. We are tied to the ocean. And when we go back to the sea - whether it is to sail or to watch it - we are going back from whence we came."

― John F. Kennedy

Remarks at the Dinner for the America's Cup Crews, September 14 1962. Not 100% scientifically correct, our blood is 1% salinity while the sea has an average of 3.5%, but I like the notion.