"Come and Go Mad" is a 1949 short story by science-fiction and mystery writer Frederic Brown. It was published in the 1951 short story collection "Space on My Hands".
I recently read the "Space on My Hands" collection, after it had been dormant on my bookshelf for many years. When I got to this story, I thought that it sounded familiar, and I soon realized that I had read it before, possibly 20 years before when I read countless science-fiction anthologies. The fact that I remembered the plot after two decades says something about the uniqueness of the story. However, reading it in context of some of Brown's other stories also made me realize some of the historical importance of the story.
The story is about a journalist named George Vine who is given the investigative assignment to infiltrate a mental hospital where something mysterious is going on: something that he will do by claiming to a psychiatrist that he has the stereotypical delusion that he is Napoleon Bonaparte. The only problem is that he actually is Napoleon Bonaparte: after a car accident, Vine woke up with Bonaparte's conscious in him, and has been feigning the role of Vine ever since. And that is just the set-up: the conclusion to the story is even more confusing, as it reveals what power was strong enough to move Napoleon's consciousness through time.
Although Frederic Brown was not quite a Philip K. Dick, his stories did include elements that transcended the space opera style of stories that were popular in the 1940s. This story involves psychological tension (is George Vine actually Napoleon, and how can he know if he is?) as well as the lingering threat of powers that go beyond human imagination. Frederic Brown was one of the first writers that shifted aliens from being a military threat to being a cosmological force beyond human comprehension. Although there are other stories in this collection that hint at that, this is one of the first stories where the idea is developed seriously.