I could have taken an educated guess, but I shook my head.

“Betting. I was careful — I didn’t want to raise any suspicions, and I sure didn’t want some bookie’s leg-breakers coming after me — but when you’ve studied up on who won every big sporting event between the summer of 1958 and the fall of 1963, you can afford to be careful. I won’t say you can live like a king, because that’s living dangerously. But there’s no reason you can’t live well. And I think the diner’ll still be there. It has been for me, and I changed plenty of things. Anybody does. Just walking around the block to buy a loaf of bread and a quart of milk changes the future. Ever hear of the butterfly effect? It’s a fancy-shmancy scientific theory that basically boils down to the idea that—”

He started coughing again, the first protracted fit since he’d let me in. He grabbed one of the maxis from the box, plastered it across his mouth like a gag, and then doubled over. Gruesome retching sounds came up from his chest. It sounded as if half his works had come loose and were slamming around in there like bumper cars at an amusement park. Finally it abated. He glanced at the pad, winced, folded it up, and threw it away.

“Sorry, buddy. This oral menstruation’s a bitch.”

“Jesus, Al!”

He shrugged. “If you can’t joke about it, what’s the point of anything? Now where was I?”

“Butterfly effect.”

“Right. It means small events can have large, whatchamadingit, ramifications. The idea is that if some guy kills a butterfly in China, maybe forty years later — or four hundred — there’s an earthquake in Peru. That sound as crazy to you as it does to me?”

It did, but I remembered a hoary old time-travel paradox and pulled it out. “Yeah, but what if you went back and killed your own grandfather?”

He stared at me, baffled. “Why the fuck would you do that?”

That was a good question, so I just told him to go on.