From: Doctor Who
Genre: Television
Who said it?: Doctor Who
The story behind the quote: This week’s quote comes from the British sci-fi program, Doctor Who. The long running program started way back in 1963 on the BBC. The program follows The Doctor and his various “companions” throughout various adventures in his time machine, the TARDIS.
The quote comes near the end of the episode entitled “The Big Bang.” The Eleventh Doctor (played by Matt Smith) visits his companion, Amy Pond (usually played by Karen Gillan but, in the scene, she was played by Caitlin Blackwood) on the night when they first met when she was seven years old. In order to save the universe (as well as restore Amy Pond’s parents back into the timeline), The Eleventh Doctor states he has to leave this current timeline.
The Doctor mentions Amy will probably not remember him at all but that’s not exactly true. She won’t remember him or the adventures they had together. Rather, she’ll be thinking of them as kind of a story she imagined. This is when The Doctor delivers the quote.
Geek wisdom: No one can live forever… physically. However, when we do pass on, there will be people who will remember us, leaving a legacy of our limited time on this world. Now, people will remember us as they will remember what we’ve done and what we did not do. So, it’s up to us regarding if we are leaving a good or a bad legacy behind us.
My Geek Wisdom 
A quote from a great movie with a lasting legacy even to this day especially in Rome comes to mind with what ya said there at the end for the Geek Wisdom:
“What we do in life echoes in eternity” – Maximus, Gladiator.
Same principle applies there too, plus as Ra’s als Ghul once said in The Dark Knight Trilogy, believe it was The Dark Knight Rises, immortality has many forms. One can be gone yet still their memory lives on in some form.