A book about literary approaches to the idea of ​​forgetting and remembering. Contrary to what we know about it, Lewis believes that forgetting has many benefits. In this book, he enumerates its benefits, methods, and how to best use it.

Many years ago, while reading about ancient oral cultures, where wisdom and history lived in tongues rather than books, I was intrigued by a brief observation. I read then that oral societies maintain their balance by discarding memories that no longer have current relevance.

My interest at the time was in memory itself, and in the valuable ways in which people and cultures preserve the past in memory. I found this observation to be contrary to what I was interested in, and it aroused my innate desire to oppose things. I began collecting scraps of other cases that proved that letting go of the past was also beneficial, as was keeping it.

It has become clear to me that this book, which finally resulted from these excerpts, is an experiment in both thought and form. As a thought experiment, it seeks to test the hypothesis that forgetting can be more useful than memory, or that memory works best in conjunction with forgetting. I do not, of course, mean that glorifying forgetting means being hostile to memory. Sometimes, any experiment worth conducting is bound to yield results, and so was the one I conducted. And, as I did, readers will no doubt pause in some cases and say, "No, we have to remember this." The irony here is that the very exhortation to resist forgetting highlights one of its functions.