Nobody knows the cause of hyper-kinetic behaviour in a child. The Ritalin seems to work to relieve the condition.

8 seconds sound clip from the The Exorcist movie soundboard.

You can hear this line at 00:34:42 in the Blu-ray version of the movie.

Quote context

[...]

- Ten milligrams a day.

- Is that a tranquillizer?

- It's a stimulant.

- A stimulant? My God, she's higher than a kite now.

- Her condition isn't quite what it seems.

- Nobody knows the cause of hyper-kinetic behaviour in a child. The Ritalin seems to work to relieve the condition.

- And as to how or why, we really don't know.

- But... her symptoms could be overreaction to depression.

- That's out of my field.

- My daughter isn't depressed.

[...]