The Enemy Within

"You can't afford the luxury of being anything less than perfect. If you do, they lose faith, and you lose command."

"The intelligence, the logic, it appears that your half has most of that. And perhaps that's where most of man's essential courage comes from for you see, he was afraid and you weren't."

"He's dead, Jim."

"Being split in two halves is no theory with me, doctor. I have a human half, you see, as well as an alien half, submerged, constantly at war with each other. Personal experience, doctor. I survive it because my intelligence wins over both, makes them live together."