An engram or memory trace is the physical imprint on the brain that forms the background of memory. The term engram was coined by the German scholar Richard Semon to describe the physical change that occurs in the brain as a consequence of a stimulus that represents a memory; it was first formulated in his book “Die Mneme”. According to Morris Moscovitch, “the engram is a supposedly physical imprint on the brain that occurs as a result of experience, which lasts and is somehow important for the subsequent expression of memory”. He argues that “the engram or memory trace is the representation of an event or experience. It is not yet a memory, but it offers the necessary (natural) condition for the emergence of memories “.
Plato, in his text “Theatitos”, has already used the metaphor of the “wax mold” in the soul, to describe the process of memorization as an imprint (“…printed, as ring points marked …”). The role of this wax mold, then, is “to capture what we want to memorize from what we may see, hear or understand ourselves.” Semon also used the term ecphory to denote the “awakening” or “rising” of the imprint from its latent state (ie the revocation of the engram) in a state of active manifestation.
Regardless of all this process, which takes place in the unconscious, man has invented other ways to maintain or even activate memory. From small objects (souvenirs) to majestic buildings were recruited to remind or assist the recall in memory of events, situations and persons. Thus, man filled his environment with souvenir creations, creating in parallel with the engrams in his brain and engrams on the external environment, which, either individually or collectively, help the expression of the memory imprint and at the same time its strengthening and maintenance.