On a Saturday afternoon last year, I sat in a 100-year-old renovated church in Zandvoort, a coastal town in The Netherlands, and ate about 30 milligrams of psilocybin, the active ingredient in magic mushrooms. This was out of character. I haven't taken drugs since my early 20s. I relish the feeling of being in absolute control, and recoil at uncertainty. Handing over my brain and sense of reality to a fungus was terrifying. And yet I had come to a legal psilocybin retreat to do just that.