On July 23, 1995, in New Mexico, the astronomer Alan Hale saw an unidentified fuzzy object in the sky. He emailed the Central Bureau for Astronomical Telegrams. In Arizona, Tom Bopp saw the same thing. He telegrammed the bureau. The comet was named Hale-Bopp the following day. Believing that a UFO was traveling behind it, thirty-eight members of The Heaven’s Gate cult committed suicide on March 26, 1997, six days before the comet reached its perihelion. 

“Where were you last night?” Yvonne asks Rick Blaine, played by Humphrey Bogart, in Casablanca. “That’s so long ago, I don’t remember.” Her follow-up: “Will I see you tonight?” To which he replies, “I never make plans that far ahead.”

“Six days, six weeks. I doubt six months,” said Donald Rumsfeld, on February 7, 2003, about the duration of the Iraq war. “Whatever happens in Vietnam, I can conceive of nothing except military victory,” Dwight D. Eisenhower said in 1967. Four years before that, Robert McNamara asserted, “The war in Vietnam is going well and will succeed.”

“The splendors of this age outshine all other recorded ages,” wrote Ralph Waldo Emerson in 1871. “I have seen wrought five miracles—namely, the steamboat, the railroad, the electric telegraph, the application of the spectroscope to astronomy, the photograph.” He died in 1882, missing the invention of the machine gun by three years, the gramophone and radar by five years, and the diesel-fueled internal combustion engine by ten years.

According to Dignitas, an end-of-life clinic located in Switzerland, 70 percent of people who begin the formal process of assisted suicide do not go through with it.