Modern medical science does not admit of such a creature. The vampire is a pure myth, superstition.

9 seconds sound clip from the Dracula (1931) movie soundboard.

You can hear this line at 00:32:27 in the Blu-ray version of the movie.

Quote context

[...]

- Read, dummkopf, where I have marked.

- Gentlemen, we are dealing with the undead.

- Nosferatu?

- Yes, Nosferatu, the undead, the vampire.

- The vampire attacks the throat. It leaves two little wounds, white with red centers.

- Dr. Seward, your patient, Renfield, whose blood I have just analyzed, is obsessed with the idea that he must devour living things in order to sustain his own life.

- Modern medical science does not admit of such a creature. The vampire is a pure myth, superstition.

- I may be able to bring you proof that the superstition of yesterday can become the scientific reality of today.

- But, Professor, Renfield's cravings have always been for small living things. Nothing human.

- As far as we know, Doctor.

- But you tell me that he escapes from his room. He is gone for hours. Where does he go?

[...]