“The Earth is so small and so fragile and such a precious little spot in the universe that you can block it out with your thumb, and you realise on that small spot, that little blue and white thing, is everything that means anything to you – all of history and music and poetry and art and death and birth and love, tears, joy games, all of it on that little spot out there and that you can cover it with you thumb. And you realize from that perspective that you’ve changed, that there’s something new there, that the relationship is no longer what it was.” 

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~ Apollo astronaut Rusty Schweickart, 

The Overview Effect, by Frank White (2014)