The package I’ve been impatiently waiting for finally arrives: A cardboard box about as tall as your average Olympic gymnast. It’s covered in yellow packing tape, stamped fragile, and has a return address in a town in the Netherlands.

Inside this box is a thing of beauty—and absurdity. It’s a one-of-a-kind puzzle created just for me by one of the greatest puzzle makers in the world. It is, almost surely, the hardest puzzle ever to exist. But before I open the box, let me tell you how the puzzle came to be, and why I think it’s not a trivial pursuit.

To do that, I’ll need to start with the Chinese ring puzzle. I was introduced to it by a puzzle collector named Wei Zhang, who, along with her husband, Peter Rasmussen, is famous in the puzzle community for having one of the world’s best collections of Chinese puzzles. Also called a “patience puzzle,” the ring puzzle dates back about 2,000 years, at least in its simplest form. What particularly fascinates me about this kind of puzzle is that it’s recursive: It gets much, much harder the more rings it has.

The goal is simple: remove a set of rings from a bar to which they’re attached. But the catch is that, for each additional ring, you have to make an exponentially greater number of moves. Solving a three-ring puzzle takes only five moves. But a six-ring puzzle takes 42 moves. A nine-ring puzzle takes 341 moves. This is because, to remove the ninth ring, you first have to repeat the entire process of removing the first ring, the second ring, the third ring, and so on. Imagine if you had to run a marathon, but at every additional mile, you had to return to the starting line and repeat the entire sequence that got you there.

You see how many miles you have to run to get to even the third-mile marker? If I actually did the diagram for 26 miles, the book this article is excerpted from would be taller than the Eiffel Tower. That’s a recursive pattern.

Turns out, the ring puzzle has several cousins in the puzzle family tree. They are called “generation puzzles,” because they take generations to solve. You’re supposed to pass them on to your kids, who pass them on to their kids, who pass them on to their kids, and on and on.

I love this idea—the ambitious scope, the connection to my descendants. I’ve always wanted an heirloom that I can hand to my sons on my deathbed. The closest I have is a blazer my gran