The risks are just too great, as this incident proves. And I was behaving responsibly.
5 seconds sound clip from the Back to the Future Part II movie soundboard.
You can hear this line at 00:37:51.594 in the Blu-ray version of the movie.
Quote context
[...]
(BOTH GASPING) I'm young! -I'm old!
- Marty! Marty! Marty, come quick! Quick!
- She encountered her older self, and went into shock, just as I predicted.
- She'll be fine. Let's get her back to 1985, and then I'm gonna destroy the time machine.
- Destroy it? What about all that stuff about humanity, where we're going and why?
- The risks are just too great, as this incident proves. And I was behaving responsibly.
- You can imagine the danger if the time machine were to fall into the wrong hands.
- My only regret is that I'll never get a chance to visit my favorite historical era, the Old West.
- But time traveling is just too dangerous.
- Better that I devote myself to studying the other great mystery of the universe: women.
[...]