In a recent interview about exorcism and spiritual possession I had to keep reminding the interviewer that in many cases possession is a welcome experience done under the supervision of a witch doctor or houngan (in the case of voodoo). When Americans think of possession the kind they’re most familiar with (thanks to novelist William Peter Blatty and filmmaker William Friedkin) is from Roman Catholic canon, but around the world possession is often sought out and seen as spiritually beneficial…