The X-Files, Season 2

Mulder:
[Mr. X hands Mulder an envelope] What's this?

Mr. X:
Data from a top secret military project. Born of the idea that sleep was the soldier's greatest enemy.

Mulder:
Grissom was conducting sleep deprivation experiments on Parris Island?

Mr. X:
Not deprivation. Eradication.

Mulder:
Why?

Mr. X:
Why else? To build a better soldier. Sustained wakefulness dulls fear, heightens aggression. Science had just put a man on the moon. So now they looked to science to win a losing war.

Mulder:
And Willig and Cole were the lab rats.

Mr. X:
Lab rats with the highest kill ratio in the Marine Corps. Four thousand-plus confirmed kills for a thirteen-man squad.

Mulder:
You think Cole's behind what's happening now?

Mr. X:
I'm not here to do your thinking, Agent Mulder. All I know is, that Augustus Cole hasn't slept in twenty-four years.

...

Mulder:
So how do I contact you?

Mr. X:
You can't

Mulder:
I may still need more.

Mr. X:
You still don't get it, do you? Closing the X-Files, separating you and Scully was only the beginning. The truth is still out there, but it's more dangerous. The man we both knew paid for that information with his life, a sacrifice I'm not willing to make.