The Past is a term used to indicate the totality of events that occurred before a given point in time. The past is contrasted with and defined by the present and the future. The concept of the past is derived from the linear fashion in which Human observers experience time, and is accessed through memory and recollection.
Freud taught us a vital life lesson, namely, that we cannot, and must not, forget the Past. What is Past in mental life may be preserved and is not necessarily destroyed, actually in mental life nothing which has once been formed can perish - everything is somehow preserved and in suitable circumstances (when, for instance, regression goes back far enough) it can once more be brought to light.