The sea
“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
The sky
"A top World War II ace once said that fighter pilots fall into two broad categories: those who go out to kill and those who, secretly, desperately, know they are going to get killed—the hunters and the hunted." - by General Nathan F. Twinning, USAF
Space
“The single simplest reason why human space flight is necessary is this, stated as plainly as possible: keeping all your breeding pairs in one place is a retarded way to run a species.” - by Warren Ellis