You know Carl Linnaeus, right? The great Swedish naturalist who
categorized plants and animals in the 1750s? He was a singular
figure in botany. But when he got a headache, he stopped being
singular. He doubled, from one Carl to two. Charles Michelet for
NPR Linnaeus suffered from migraine attacks, and according to
neurologist Macdonald Critchley, when his headaches came on,
he'd hallucinate. A second, phantom Carl Linnaeus would often
appear — seen only by the first — and would float about, doing
whatever Real Carl was doing. So Linnaeus would be in his
garden, checking out a plant or plucking a flower, and he could
see, at a respectful distance, the Other Carl stooping and
plucking the same way at the same time. Linnaeus didn't fear his
phantom; in fact he got used to it. Charles Michelet for NPR As
Critchley describes it, the phantom might sit in Linnaeus' seat
at his library desk, and Real Linnaeus, would, presumably,
ignore him. One time, Professor Linnaeus was lecturing at his
university and decided to