The grandfather of present-day regression work

was Freud, with his innovative idea that making the unconscious conscious would restore choice and bring healing. This concept emerged during a period of trial and error when Freud was tapping repressed memories of early childhood, first through hypnosis and then through free association. We can appreciate the innovation and the courage of that search when we conceptualize a world in which only novelists were sure there was an unconscious. 

Freud abandoned his original attempt to uncover traumatic memories through hypnosis, a nebulous technique at that time, because the connection between original trauma and later symptoms was not yet evident. He himself discovered this link while working with free association. He called it psychic determinism. It was his conceptual masterpiece, and it has influenced nearly all subsequent psychotherapy and is the foundation of regression work. Current suggestions in regression therapy, such as “Go back to the time when this problem first occurred,” are based on this certainty that what we experienced earlier dictates our current behavior.

Freud’s theory that memories of early childhood could be recovered and used therapeutically drew scornful reactions, but he persisted, though near the beginning he had to jettison his original conception of child abuse. As Galileo, who, in order to avoid being burned at the stake, agreed that the sun moved around the earth, Freud, to avoid being driven from Vienna, was forced to say that the tortured memories of his patients were fantasies. The importance of such memories currently permeates psychological thinking - witness to the often long hiatus between innovative proposals and their eventual acceptance.

-Regression Therapy, Volume 1 by Winafred Blake Lucas Ph. D. Published in 1993.