A major defining factor was my wanting him to be part of the DC Universe. Because if someone as powerful as the Sandman was running all the dreams in the world, a natural question would be Why haven’t we heard about him by now?The answer I came up with was He’s been locked away. And that solution formed an image in my head of a naked man in a glass cell.My next question was How long had he been trapped there? The movie hadn’t been made yet, but I’d read Oliver Sacks’s book a few months earlier, so I knew about the encephalitis lethargica, or sleepy sickness, that had swept Europe in 1916. Scientists to this day don’t understand what caused it, and I loved the idea of blaming it on the Sandman’s imprisonment, so I determined the length of his stay to be seventy-two years—ending in late 1988, when the series debuted.And so on; each plot point just seemed to naturally lead to the next one.