“In Turkish we have a special tense that allows us to distinguish hearsay from what we’ve seen with our own eyes,” wrote Orhan Pamuk in Istanbul: Memories and the City. “When we are relating dreams, fairy tales, or past events we could not have witnessed, we use this tense. It is a useful distinction to make as we ‘remember’ our earliest life experiences, our cradles, our baby carriages, our first steps, all as reported by our parents, stories to which we listen with the same rapt attention we might pay some brilliant tale of some other person.”

Malingering amnesia, in which a person fakes symptoms of memory loss, is often associated with attempted financial gain, typically among personal-injury claimants. According to a 2003 study, 29 percent of criminals sentenced to life imprisonment claimed at their trials that they suffered from amnesia. A visual recognition test, such as the Test of Memory Malingering, can be used to detect fraud of this kind.

“There is one thing at which I cannot sufficiently wonder,” wrote Pliny the Elder, “that of some trees, the very memory has perished, and even the names recorded by authors have passed out of knowledge.”

“When Simonides or someone offered to teach him the art of memory,” Cicero noted in his De Finibus, the Athenian politician Themistocles “replied that he would prefer the art of forgetting. ‘For I remember,’ said he, ‘even things I do not wish to remember, but I cannot forget things I wish to forget.’ ”