In one variation of a popular paradox, a friend tells you that she’ll give you a present sometime next week, but that you won’t be able to predict the day on which you’ll receive it.

This is puzzling. If she waits until Saturday, the end of the week, it will be obvious that you must receive the gift on that day, as no other day remains possible. But if we exclude Saturday then the same argument could be used to exclude Friday, and so on back to Sunday. It seems that the friend’s declaration can’t be true — her gift can’t be unexpected.

David Morice offers one possibility that he called “Zeno’s solution”: Your friend, wearing a precision wristwatch, presents the gift in the moment precisely between Friday and Saturday. No reasoning has led you to expect this, so you’re surprised.

(David Morice, “Kickshaws,” Word Ways 27:2 [May 1994], 106-116.) (See the link — Morice offers three other solutions as well, “but I expect that each is logically flawed.”)

The delta of Argentina’s Paraná River contains a rotating eye. “El Ojo” is a circular floating island 118 meters wide that spins in place within a slightly larger circular lake. It’s been there, silently turning, for at least 20 years — Google Earth confirms its presence in 2003.

See “A Revolving Ice Cake.”

In Three Men in a Boat (1889), the narrator reads a medical textbook and is stricken with the certainty that he has every condition described there:

I came to typhoid fever — read the symptoms — discovered that I had typhoid fever, must have had it for months without knowing it — wondered what else I had got; turned up St. Vitus’s Dance — found, as I expected, that I had that too … I plodded conscientiously through the twenty-six letters, and the only malady I could conclude I had not got was housemaid’s knee.

This is a recognized phenomenon. In 1908, Boston neurologist George Lincoln Walton reported:

Medical instructors are continually consulted by students who fear that they have the diseases they are studying. The knowledge that pneumonia produces pain in a certain spot leads to a concentration of attention upon that region which causes any sensation there to give alarm. The mere knowledge of the location of the appendix transforms the most harmless sensations in that region into symptoms of serious menace.

In 2004 University of Toronto psychiatrist Brian Hodges noted that “medical students’ disease” is said to afflict 70 to 80 percent of students, often invading their dreams. Walton wrote, “The sensible student learns to quiet these fears, but the victim of ‘hypos’ returns again and again for examination, and perhaps finally reaches the point of imparting, instead of obtaining, information, like the patient in a recent anecdote from the Youth’s Companion:”

It seems that a man who was constantly changing physicians at last called in a young doctor who was just beginning his practice.

‘I lose my breath when I climb a hill or a steep flight of stairs,’ said the patient. ‘If I hurry, I often get a sharp pain in my side. Those are the symptoms of a serious heart trouble.’

‘Not necessarily, sir,’ began the physician, but he was interrupted.

‘I beg your pardon!’ said the patient irritably. ‘It isn’t for a young physician like you to disagree with an old and experienced invalid like me, sir!’

In 1589, German farmer Peter Stumpp confessed that the devil had given him a belt that would give him “the likeness of a greedy, devouring wolf, strong and mighty, with eyes great and large, which in the night sparkled like fire, a mouth great and wide, with most sharp and cruel teeth, a huge body, and mighty paws.”

Over the course of 25 years, he said, he had killed and eaten 14 children, two pregnant women, and their fetuses.

The confession was extracted on the rack, but the magistrate didn’t care: Stumpp was broken, hobbled, beheaded, and burned.

(The Damnable Life and Death of One Stubbe Peeter, a Most Wicked Sorcerer, 1590.)

In 1600, actor William Kempe traveled from London to Norwich, a distance of 177 kilometers. Why is that notable? He morris-danced the whole way, a feat that took nine days spread over several weeks. He published an account of the journey to convince doubters:

Vpon Fryday morning I set on towardes Thetford, dauncing that tenne mile in three houres; for I left Bury somewhat after seauen in the morning, and was at Thetford somewhat after ten that same forenoone. But, indeed, considering how I had been booted the other iourneys before, and that all this way, or the most of it, was ouer a heath, it was no great wonder; for I far’d like one that had escaped the stockes, and tride the vse of his legs to out-run the Constable: so light was my heeles, that I counted the ten mile no better than a leape.

He’s remembered for an even more distinctive accomplishment — he was one of the original stage actors in Shakespeare’s early dramas.

(Thanks, Tyler.)

A few details from Christine Quigley’s Conjoined Twins (2003):

• Filipino twins Simplicio and Lucio Godino, above, had separate cars, each with the steering column on the appropriate side, “but Lucio had the better arrangement, since in the Philippines the cars passed each other on the left as in England.”
• When Mary and Margaret Gibb boarded the ocean liner Majestic in 1930, they attempted to use a single passenger ticket. The White Star Line denied their request, basing its decision on the number of meals they’d consume.
• “In a case in Paris in the seventeenth century of a conjoined twin stabbing a man to death, the sentence of death was commuted rather than executing the innocent twin.”
• Ronnie and Donnie Galyon had two Social Security numbers and two voter registration cards but one passport.
• Yvonne and Yvette McCarther didn’t share a wristwatch, lighter, or purse, “but their purses contained matching sets of everything from vitamin jars to wallets containing the same family photos.” “I speak for myself, and she speaks for herself,” said Yvonne.
• Abigail and Brittany Hensel received two birth certificates, but both read “first” as to order of birth. If either misbehaved, both were sent to their room.
• Separated from her conjoined sister Maria in 1965, six-year-old Giuseppina Foglia asked, “Am I really myself?” She told her sister, “You’re so far away!”

Psychologist Nancy Segal writes that “[W]hile most identical twins get along well, many conjoined twins are are masters at negotiation, cooperation and compromise.” By contrast, when unjoined sisters Patricia and Madeleine Infante connected themselves with a wire and entered show business as “Violet and Daisy Milton,” they ended up quarreling with their manager and destroying a sign billing them as “the only original American Siamese twins.” They were charged with vandalism, ending their career.