I was reading a collection of articles about Rock n Roll, and in one of them, ("The Sound of Acid" by Jon Savage) he does a chillingly good description of what drugs can do to you. Here goes:
"There are many risks in experimenting with your consciousness. If you're going to take a drug which makes your soul manifest, you may get more than you bargained for. You maybe confronted with demons which you didn't know existed or externally hostile situations which tip you into madness which, while temporary, is nonetheless real. You have seen God through a drug rather than the discipline of spiritual thought: this can leave a serious hole in your reality."
Having tried pot once, I can identify with it. While it's a great experience, I will think ten times before I try it again, as my reality is something that I don't want to mess with. There are some doors that should never be opened, unless you're pretty sure you've got nothing to lose.