My name is Bobby Singer. In twenty-four hours I'm gonna lose my memory. So here's everything you need to know.

Monsters, demons, angels, vampires, the boogeyman under your bed: I've seen it, I've hunted it, I've killed it. I'm not the only hunter out here, but there aren't as many as there used to be. Not near as many as there need to be. I've learned everything I can about every damned critter that walks, crawls, or flies, and I'm not gonna let that all be for nothing. I'm not going down without a fight. I'm not letting everything I've learned disappear. So that's what you're holding in your hands--everything I know. Anything that'd be useful for Sam, Dean, and the hunters that come after me.

It's a guide to hunting...it's a guide to me. My last will and testament. Ya idjits.