Going to sleep tonight.

Ghosts.
The question is not whether they exist or not, but rather if your sanity is ready to make them part of your reality.

>>5
In all of 20 billion or so of mankind, has anyone ever made a promise and been able to keep it after death? Even something simple like writing a message?

Either they don't exist, or they lose who they are and become violent murders who love killing. Cause that's what ghosts seem to do. I've sadly never heard of a nice ghost who tells his loved ones winning lottery numbers.