The country is entering a new and precarious phase, in which the central question about President Donald Trump is not whether he is coming unstrung, but rather just how unstrung he is going to get.

The boiling mind of Trump has spawned a cottage industry for cognitive experts who have questioned whether he is, well, all there. But as the impeachment inquiry barrels ahead on Capitol Hill, several associates of the president, including former White House aides, worry that his behavior is likely to get worse. Angered by the proceedings, unencumbered by aides willing to question his judgment, and more and more isolated in the West Wing, Trump is apt to lash out more at enemies imagined and real, these people told me. Conduct that has long been unsettling figures to deteriorate as Trump comes under mounting stress. What unfolded Wednesday inside the West Wing’s walls might be only a foretaste of what House Speaker Nancy Pelosi described that day, after a meeting with Trump, as a presidential “meltdown.”

Mick Mulvaney's job was in danger even before his disastrous press conference yesterday, and his equally disastrous attempt to walk that performance back. The fumble could not have been more poorly timed: According to multiple current and former White House officials, many of whom spoke on the condition of anonymity to relay private conversations, Trump has been steadily souring on Mulvaney for weeks.

In his maiden briefing-room appearance yesterday, the acting White House chief of staff acknowledged that the Trump administration had held up military aid to Ukraine in exchange for a politically motivated investigation—a quid pro quo that Trump has repeatedly insisted never took place, and is the subject of the House Democrats’ impeachment inquiry.

In 2007, Carlo Carandang, then an attending physician at a hospital in Halifax, Nova Scotia, saw a most unusual patient: an 8-year-old boy who had recently adopted some strange beliefs, all while losing 18 pounds. The boy thought that nurses were “evil,” and that he could inject other people with his fat cells simply by walking past them.

The boy’s symptoms had begun a few months prior. After his school held a lesson on healthy eating, he started to scrutinize food labels and avoid fat and carbs, according to Carandang, who now works as a data scientist. The boy worried that he was too fat, and he would examine his stomach in the mirror throughout the day. He grew suspicious of what his mother might be putting in his food and began preparing all of his own meals. Before long, he was eating just 200 calories a day.

Several weeks ago, I met up with a friend in New York who suggested we grab a bite at a Scottish bar in the West Village. He had booked the table through something called Seated, a restaurant app that pays users who make reservations on the platform. We ordered two cocktails each, along with some food. And in exchange for the hard labor of drinking whiskey, the app awarded us $30 in credits redeemable at a variety of retailers.

I am never offended by freebies. But this arrangement seemed almost obscenely generous. To throw cash at people every time they walk into a restaurant does not sound like a business. It sounds like a plot to lose money as fast as possible—or to provide New Yorkers, who are constantly dining out, with a kind of minimum basic income.

It is easy to look at today’s crop of sinking IPOs—like Uber, Lyft, and Peloton—or scuttled public offerings, like WeWork, and see an eerie resemblance to the dot-com bubble that popped in 2000.

• Both then and now, consumer-tech companies spent lavishly on advertising and struggled to find a path to profit.

• Both then and now, companies that bragged about their ability to change the world admitted suddenly that they were running out of money.

• Both then and now, the valuations of once-heralded tech enterprises were halved in a matter of weeks.

• Both then and now, there was a widespread sense of euphoria curdling into soberness, washed down with the realization that thousands of workers in once-promising firms were poised to lose their jobs.

Just under a century ago, the Soviet Union embarked on one of the strangest attempts to reshape the common calendar that has ever been undertaken. As Joseph Stalin raced to turn an agricultural backwater into an industrialized nation, his government downsized the week from seven to five days. Saturday and Sunday were abolished.

In place of the weekend, a new system of respite was introduced in 1929. The government divided workers into five groups, and assigned each to a different day off. On any given day, four-fifths of the proletariat would show up to their factories and work while the other fifth rested. Each laborer received a colored slip of paper—yellow, orange, red, purple, or green—that signified his or her group. The staggered schedule was known as nepreryvka, or the “continuous workweek,” since production never stopped.

After giving birth to a baby, a young woman told her nurses at Boston Medical Center that she was having pain in her hip. That happens sometimes after births, says Ali Guermazi, one of the doctors involved. As he recounts the case from a few years ago, he looked at X-rays and saw a small amount of extra fluid in the joint. Otherwise things looked normal. “We injected her hip with steroids, hoping to help with the pain,” Guermazi says. They seemed to help, and the women went home with her baby.

Guermazi didn’t think more of it until the woman returned to the hospital six months later, unable to walk. “The head of her femur was gone,” says Guermazi, who is now the chief of radiology at VA Boston Healthcare System. The bone appeared to have simply vanished. The new mother needed a total hip replacement. “We didn’t know what happened, and still can’t know for certain,” Guermazi says. “But I feared it was related to the injection.”

On a third-down play last season, the Washington Redskins quarterback Alex Smith stood in shotgun formation, five yards behind the line of scrimmage. As he called his signals, a Houston Texans cornerback, Kareem Jackson, suddenly sprinted forward from a position four yards behind the defensive line.

The Wildlife Photographer of the Year competition, founded in 1965, is an annual international showcase of the best in nature photography. This year, the contest attracted more than 48,000 entries from 100 countries. Wildlife Photographer of the Year is developed and produced by the Natural History Museum, London. The owners and sponsors have once again been kind enough to share the following 15 winning images from this year’s competition. The museum’s website has images from previous years and more information about the current contest and exhibition. Captions are provided by the photographers and WPY organizers, and are lightly edited for style.

Where in the pantheon of American commercial titans does Jeffrey Bezos belong? Andrew Carnegie’s hearths forged the steel that became the skeleton of the railroad and the city. John D. Rockefeller refined 90 percent of American oil, which supplied the pre-electric nation with light. Bill Gates created a program that was considered a prerequisite for turning on a computer.

At 55, Bezos has never dominated a major market as thoroughly as any of these forebears, and while he is presently the richest man on the planet, he has less wealth than Gates did at his zenith. Yet Rockefeller largely contented himself with oil wells, pump stations, and railcars; Gates’s fortune depended on an operating system. The scope of the empire the founder and CEO of Amazon has built is wider. Indeed, it is without precedent in the long history of American capitalism.