Religions make some pretty outrageous claims. Many traditions assert that angels have visited important people here on Earth. Most insist that life after death is real. But one fact about religious claims that’s often lost in contemporary debates is that even the wildest religious propositions don’t just come from out of the blue. They often arise, as theologian Friedrich Schleiermacher pointed out, from religious experiences. And researchers from Israel and Switzerland think that many of these experiences may be triggered by high-altitude environments on mountainsides.