Dexter, Season 1

Dexter:
[voiceover] Harry taught me that death isn't the end. It's the beginning of a chain reaction that will catch you if you're not careful. He taught me that none of us are who we appear to be on the outside. But we must maintain appearances to survive. But there was something Harry didn't teach me. Something he didn't know, couldn't possibly know. The willful taking of life represents the ultimate disconnect from humanity. It leaves you an outsider, forever looking in, searching for company to keep.