You know what memory is. Everybody does. You know facts from life, or learn them from a textbook, and they are in your memory – for example, “grass is green,” or “Paris is the capital of France.” You take a trip to Paris, visit the Eiffel Tower, and when you get back home the event is still with you, in your memory (like, “In Paris we climbed the Eiffel Tower; it was amazing!”) Pretty easy. Remembering requires no effort, it comes perfectly naturally to all healthy people, and nobody makes anything of it. Except some psychologists and other students of the brain/mind.

I have studied memory all my life. I have done experiments, had thoughts about memory's nature, proposed new theories, created new concepts, and made up fresh terms to go with the concepts. I have also read a lot of what other students of memory have written. It all has been fruitful and fun, and made for a satisfying life.

In the science of memory, as in other branches of science, every now and then something interesting is discovered. By “interesting” I mean that when the discoverers tell others about it, the others do not believe them. I discovered a new kind of memory that turned out to be “interesting,” and have spent much of the rest of my life trying to explain it to those who resisted the idea.

I cannot relate the complete story about how the discovery happened. But its thumbnail summary goes like this: Many years ago, a colleague of mine, at a university far away from Toronto, invited me to organize a conference in his research center, on the theme of “organization of memory.” I asked a group of respected specialists to come and give talks. After the conference all speakers wrote a chapter for the book based on the conference proceedings. I had not given a talk because I was no longer interested in organization of memory, but I edited the book along with a young colleague. Among the submitted chapters there were three that claimed to discuss “semantic” memory. Try as I might, I could not understand what the authors were talking about. It was very different from what I knew of memory. I relieved my frustration by writing a chapter for the book about a new idea I had about memory.