I don't know, Doc. You're the one that's always saying, you know, it's not good to know too much about your own destiny.

Marty Mcfly (Michael J. Fox)

5 seconds sound clip from the Back to the Future Part III movie soundboard.

You can hear this line at 00:13:11.132 in the DVD version of the movie.

Quote context

[...]

(GEARS ENGAGING, MOTOR WHIRRING)

- You know, when I was a kid, I always wanted to be a cowboy.

- And now, knowing I'm gonna spend my future in the past, it sounds like a wonderful way to spend my retirement years.

- It just occurred to me, Marty, since I end up in 1885, perhaps I'm now in the history books.

- I wonder. Could I go to the library and look myself up in the old newspaper archives?

- I don't know, Doc. You're the one that's always saying, you know, it's not good to know too much about your own destiny.

- You're right, Marty. I know too much already. Better that I not attempt to uncover the circumstances of my own future.

- Copernicus. Come on, boy!

- I'll get him, Doc. Copernicus! Copernicus, come on. Let's go home, boy.

- What's wrong? What's wrong, Copernicus? Come on. Come on, let's go home. Come on. Come on.

- Doc! Doc! Come here! Quick!

[...]