I read about vampires years ago. I always thought it was the product of an over-fertile imagination. Would that it were, Mr. Kent.

10 seconds sound clip from the Dracula: Prince of Darkness movie soundboard.

You can hear this line at 01:02:45.840 in the Blu-ray version of the movie.

Quote context

[...]

- Where's Charles?

- You don't need Charles.

- Stop! Let her go!

- Dear Charles, let me kiss you.

- Oh, Charles!

- Diana, get away!

- I warned you not to go anywhere near the castle, Mr. Kent.

- I read about vampires years ago. I always thought it was the product of an over-fertile imagination. Would that it were, Mr. Kent.

- Here in the Carpathian Mountains, vampirism was an undisputed fact. And the fountainhead of this obscene cult was Dracula himself.

- I thought we'd seen the last of him. The last record we have of him is... Here it is. Ten years ago.

- From what you tell me, it was your unfortunate brother who provided the life force for his resurrection.

- Then... I must kill him.

- Not kill. He is already dead. He is an undead, Mr. Kent. He can be destroyed, but not killed.

[...]