There's only one way to be positive. I'd have to see the dinosaur's droppings.
8 seconds sound clip from the Jurassic Park (1993) movie soundboard.
You can hear this line at 00:51:55 in the Blu-ray version of the movie.
Quote context
[...]
- These are dilated. They are?
- That's pharmacological. From local plant life.
- Yes. We know they're toxic, but the animals don't eat them.
- There's only one way to be positive. I'd have to see the dinosaur's droppings.
- That storm center hasn't dissipated or changed course.
- It's not worth taking the chance.
[...]