The source of the Thames doesn’t look like it. It looks like a pasture, and not even a soggy pasture. Not a single water plant grows there. If it weren’t for an old well, filled up with stones, it would be impossible to even locate the spot. Cows, not being interested in stones, wander lazily across and around the source, munching buttercups and Queen Anne’s lace, unaware that anything significant is beginning beneath their feet.

Science is even less obvious. It starts with an apple falling, a teakettle boiling. Alex Fleming, taking a last glance around his lab as he left for a long weekend, wouldn’t have seen anything significant in the window left half open, in the sooty air from Paddington Station drifting in. Getting ready to gather up his notes, to tell his assistant to leave everything alone, to lock the door, he wouldn’t have noticed that one of the petri dishes’ lids had slid a fraction of an inch to the side. His mind would have already been on his vacation, on the errands he had to run, on going home.

So was mine. The only thing I was aware of was that Flip had thoughtfully crumpled each clipping into a wad before stuffing them into the trash can, and that there was no way I could get them all smoothed out tonight, and, as a result, I was not only oblivious to the first event in a chain of events that was going to lead to a scientific discovery, but I was about to miss the second one, too. And the third.

I set the trash can on the lab table on top of my jitterbug research, sealed the top with duct tape, stuck on a sign that said “Do not touch. This means you, Flip,” and went out to my car. Halfway out of the parking lot I thought about Flip’s ability to read, turned around, and went back to my office to get the trash can.