Why is it prohibited to put on and take off two garments at the same time? It seems that it comes from a kabbalistic idea that I don't quite understand.
Dear Ira Widman,
The Ben Ish Chai explains that this is because a certain spiritual existence is situated around the human body and between the layers of garments he wears. It is a sort of shielding against any spiritual mishap. One has to remove pieces of clothing one at a time for this entity to depart, and to put them on also one at a time for it to take its place again. If one removes two pieces of clothing at once he is "trapping" this entity which after being submitted to such a humiliation will not return again. Subsequently the human will be unguarded against spiritual mishap, i.e., forgetfulness.