I'm re-reading The Nature of Personal Reality by Jane Roberts and the spirit of Seth, which she channeled. I don't recall when I read the original book, only that it was sometime back in the 2000s. In reading the book now I'm struck by how much it focuses on two areas of interests I have, working with the body as a magical tool and space/time magic. I'm going to focus on the latter and specifically on a statement made in the book, "The Present is the Point of Power." It's worth spending some time considering that statement as it relates to space/time magic, but also how we conceive of the present.
The present is the moment we are experiencing, in a linear sense, as a sense of "now", but the present is also comprised of all your past experiences, beliefs, attitudes etc., and yet it is also what enables us to change what we gain from the past. Seth points out that what you believe about your past is what you get from it and what contributes to what you make of the present. While this might seem like self-evident advice, I think its a useful point to consider in relationship to retroactive magic and space/time magic in general.
Memories are shaped by belief. If you have a negative belief about yourself, then you'll find memories to justify that belief. Likewise if you have a positive belief, you'll find memories to support that belief. If you want to change memories, part of what you need to change about them is the underlying attitude and belief that you've invested in yourself. Your present sense of self is shaped by your memories and what you tell yourself about who you are. Conversely your present shapes your memories as well, so that if we want to change the sense of self and what we identify with, then we should look toward changing the memories we pick or creating entirely new ones and inserting them into the past as events that have actually happened.
Memory is part of imagination and so it is not impossible to create a memory. We imagine memories all the time. We might call them fantasies or daydreams or whatever else, but they can be memories. Imagine yourself as a younger person doing an activity, or spending time with someone, and in that memory insert the new beliefs and values you wish to have. Then insert that memory into your past among other memories, allowing it to spread the beliefs and values into the other memories, changing what occurred so that the present and your sense of self is also changed.
Our sense of time is static, but the actual experience of time is fluid and if we know this then the present does become the point of power because we aren't constrained by false linearity, but rather recognize that any given moment can become the present through the use of imagination and memory. When we insert a memory into the past or change an existing one, what is being changed is the identity of the person. You may discover new possibilities in the present as a result or look at your experiences with a new perspective about yourself and others that helps you navigate situations you are in. When we take charge of the present and use it to change the past, when we recognize that our experiences aren't set in stone, but can be shaped by what we invest in them, we unlock the potential of imagination and memory to be more than just something that we fantasize or remember. We become what we identify with and use that to discover what we can become.