I picked the pebbles up off the table, two in my right hand and two in my left. The fifth stayed on the table.
— How many? — I asked.
— Two green ones in one hand and two green ones in the other.
— And together?
— I’d guess three. Green stones, born out of adding yellow to blue, tend to vanish under any subsequent addition. If you want to demonstrate a different result, go ahead and add them.
I shrugged and poured the pebbles from my right hand into my left. Sparks flashed again, and two yellow pebbles and one turquoise one ended up on my palm.
— Cheap tricks, — I concluded.
— Not at all. Do you agree there’s logic to how these stones combine?
The gentleman took the green pebble off the table and set it in my palm. It flashed and turned blue, and so did the turquoise one. Now I had two yellow pebbles and two blue ones on my palm.
Hard to argue with the logic.
— Another example. There are questions that can have two mutually exclusive correct answers.
— How’s that?
— Roughly speaking, you could answer a question yes, or you could answer it no. Either way, both answers turn out correct.
— That’s not possible.
— Watch.
The gentleman stood up while somehow still sitting in his chair. How? Ah. He’d split in two.
Cheap tricks!
I watched it happen.
Now there were two interlocutors. One sat across from me like a stern professor, in the exact same pose as a second before. The other stood facing me, wearing a Cheshire-cat grin.
— Let’s continue the conversation, — said the one seated.
— Don’t mind, do you? — the one standing asked me.
I shrugged. Go for it!
— So then, a wager, — the seated one proposed.
— I accept, — the standing one answered.
I nodded at both of them.
The standing one pulled a hundred-dollar bill from his pocket and set it on the table, saying: «I’ll give it to whoever guesses what I’m about to do.»
Total nonsense! What could he possibly do? He’d do literally anything except whatever I said. A guaranteed win for the standing one.
Both of them, standing and seated, looked at me. I kept shifting my gaze between the two, not knowing how to put my thought into words. The seated one smiled:
— If Roman doesn’t mind, I’ll try to guess what you’ll do. You won’t give this money to me.
Whoa!
Now that was a trick! If the standing one wanted to win the bet, he had to hand the money to the seated one, and then take it back, since the seated one had guessed wrong. But then it would turn out he never actually gave the money away. And conversely, for the seated one to win the bet, he’d have to not take the money now, and take it later instead. No…
Not like that…
Then how?
I froze, hunting for an answer. My thoughts kept lurching around, never landing on a common denominator. The seated one rose from the table and reached a hand toward the standing one. The other reached out too. The hundred-dollar bill flew up and hung in midair, exactly halfway between them. The two gentlemen announced in unison:
— As always, I’m right.
Impossible! They stood there with hands outstretched, the hundred-dollar bill suspended in the air between them. There was nothing in the terms of the bet to determine who’d lost and who’d won. Both of them had won at once, and lost at once too. I shrugged.
The two gentlemen smiled, stepped toward each other, and merged back into one. The bill, banking through the air, dropped onto the table. The gentleman picked it up and, with a wave of his hand, turned it into a pearly sphere.
