i sank to the ground , leaning my head back against the smooth bark of a tree i did n't recognize . here 's the thing -- -if we succeed , we do n't just save the world . a beautiful and peaceful blue moon was in the sky . how long have we got , doc ? when i am asked to give my favorite color , for just the briefest , tiniest of seconds my mind flashes on a sky the color of polished silver , and i think i hear a word- gray - whispered quietly into my ear . 