And just as all things will be repeated in the future, all things now happening happened a million times before. Some few people in every town, in their dreams, are vaguely aware that all has occurred in the past. These are the people with unhappy lives, and they sense that their misjudgments and wrong deeds and bad luck have all taken place in the previous loop of time. In the dead of night these cursed citizens wrestle with their bedsheets, unable to rest, stricken with the knowledge that they cannot change a single action, a single gesture. Their mistakes will be repeated precisely in this life as in the life before. And it is these double unfortunates who give the only sign that time is a circle. For in each town, late at night, the vacant streets and balconies fill up with their moans.
From Einstein’s Dreams by Alan Lightman.