You see, a great deal is known about the vampire bat, but details of these re-animated bodies of the dead, the undead, as we call them, are so obscure, that many biologists will not believe they exist.

Abraham Van Helsing (Peter Cushing)

13 seconds sound clip from the Horror of Dracula (1958) movie soundboard.

You can hear this line at 00:57:39.708 in the DVD version of the movie.

Quote context

[...]

- There's so much in Jonathan's diary I don't understand.

- Can Dracula really be as old as it says here?

- We believe it's possible. Vampires are known to have gone on from century to century. Records show that Count Dracula could be 500 or 600 years old.

- Another thing. I always understood that, if there were such things, they could change themselves into bats or wolves.

- That's a common fallacy.

- The study of these creatures has been my life's work. I've carried out research with some of the greatest authorities in Europe. And yet, we've only just scratched the surface.

- You see, a great deal is known about the vampire bat, but details of these re-animated bodies of the dead, the undead, as we call them, are so obscure, that many biologists will not believe they exist.

- Of course, you are shocked and bewildered. How can you expect to understand in so short a time?

- But you've read and experienced enough to know that this unholy cult must be wiped out. I hope perhaps that you will help me.

- I'll do anything you say.

- Thank you.

- Of course, we do know certain things. You witnessed one a little while ago.

[...]