When I first heard this song, I wasn't really sure what it was about. Someone told me it was about a post-apocalyptic meeting between the last man and woman on Earth. After I heard that, I listened to the song and, yeah, that fits - the words and the mood set by the melody. But I was wondering, what's the background on this song? Is there more to the story? I know the Grateful Dead did not write it. When did they start playing it? How did they come across it?