What constitutes a hole? We recognize and refer to holes as we do ordinary material objects, but a hole doesn’t seem to have a material existence. A hole has a “host” (say, a doughnut), and it may have a “guest” (say, air), but neither of these is itself the hole. Somehow the hole is a something that’s made of nothing.

In a 1969 essay by David and Stephanie Lewis, Argle and Bargle argue over a hole in a piece of Gruyère cheese:

Bargle. How can something utterly devoid of matter be made of matter?

Argle. You’re looking for the matter in the wrong place. (I mean to say, that’s what you would be doing if there were any such things as places, which there aren’t.) The matter isn’t inside the hole. It would be absurd to say it was: nobody wants to say that holes are inside themselves. The matter surrounds the hole. The lining of a hole, you agree, is a material object. For every hole there is a hole-lining; for every hole-lining there is a hole. I say the hole-lining is the hole.

Bargle. Didn’t you say that the hole-lining surrounds the hole? Things don’t surround themselves.

Argle. Holes do. In my language, ‘surrounds’ said of a hole (described as such) means ‘is identical with’. ‘Surrounds’ said of other things means just what you think it means.

Bargle. Doesn’t it bother you that your dictionary must have two entries under ‘surrounds’ where mine has only one?

Also: If I fill in a hole in the ground, have I destroyed it? If I dig again in the same place, am I creating a new hole or restoring the old one?

(David Lewis and Stephanie Lewis, “Holes,” Australasian Journal of Philosophy 48:2 [August 1970], 206-212.)

In 1985, Levon Arakelyan’s wife asked him to dig a potato cellar in their basement in Arinj, Armenia. He did this, and then continued digging for 23 years. At his death in 2008 he’d produced a network of rooms, steps, and corridors that extended 21 meters beneath the couple’s two-story house. A builder by trade, he did all of this with hand tools. Today his widow runs a small museum and gives tours of her late husband’s strange obsession. More photos here.

Three different Japanese texts of the early 19th century refer to a “hollow ship” that arrived on a local beach in 1803. A white-skinned young woman emerged, but fishermen found that she couldn’t communicate in Japanese, so they returned her to the vessel, which drifted back to sea.

This seems to be a folktale, though it’s an oddly specific one — the texts give specific dates (Feb. 22 or March 24) and give the dimensions of the craft (3.3 meters high, 5.4 meters wide), which was shaped like a rice pot or incense burner fitted with small windows. Reportedly the woman carried a small box that no one was allowed to touch.

But the place names mentioned appear to be fictitious; most likely the story is merely an expression of the insularity of the Edo period. One thing the ship wasn’t is a UFO — it never left the water, but simply floated away.

The clock on Bolivia’s congressional building runs counterclockwise.

Foreign Minister David Choquehuanca said the “clock of the south” had been adopted to affirm the country’s “southernness” and to encourage Bolivians to question norms and think creatively.

“Who says that the clock always has to turn one way?” he asked at a news conference in 2014. “Why do we always have to obey? Why can’t we be creative?”

Perhaps he’d been inspired by Venezuela, where in 2006 president Hugo Chávez raised a new national flag on which a white horse gallops left instead of right, “representing the return of Bolivar and his dream,” and the following year he put the nation’s clocks back half an hour “so that our bodies and above all our children take better advantage of sunlight and adapt the biological clock.”

In 1998, thousands of pigeons mysteriously went missing during two separate races in Virginia and Pennsylvania. More than 2,200 birds vanished, amounting to an 85 percent loss rate. The weather was calm, and it’s normal for a few birds to disappear, but the rate is usually closer to 5 percent.

It’s known that pigeons navigate by the sun and by sensing magnetic fields, but neither of those seems to be the culprit here. “Every year or so, you have one race like this where many disappear,” Cornell zoologist Charles Walcott told the Chicago Tribune. “But what is unusual is to lose so many birds from several races at the same time. What’s going on now is quite mysterious.”

Related: In 2010 a racing pigeon named Houdini disappeared during a 224-mile race in Britain and turned up five weeks later in Panama, 5,200 miles away.

“I was gobsmacked. I didn’t even know where Panama was,” owner Darren Cubberley told the Daily Mirror. “I’ve no idea how Houdini got there — I can only assume she hitched a lift on a ship across the Atlantic.”

The bird, reportedly in “perfect shape,” would have been too expensive to return, so she remained with Gustavo Ortiz, on whose roof she’d landed. At last report she was learning Spanish.