Years ago I dreamt I was in a pool swimming under water. The dream was so vivid, I can still remember the pale legs around me and the crystalline blue water. As I was swimming I began to run out of air and no matter how hard I tried to swim to the surface, I couldn’t make it. As I neared the end of my breath, ready to collapse, I broke through the surface and sat straight up in bed. It was the only time I’ve ever woken from a dream like that, and after decades I still remember it. Even then I knew it was significant, but only in…