[mel!ssa]

Yeah, whatever.

I think what your instructor meant was something along the lines of, the exercising part of yoga is fine, beneficial and all that, but the meditation part, if you are a true master at it and can manage to completely and totally empty your head (and not many can do this completely), then yes it leaves the way open for demons to enter. It doesn't happen very often, and not as much as it used to, but it does happen.