So yesterday (which is the past) I went out to the pub with a couple of friends. This past is created by my current observation of it and understanding of it. If I stop observing or understanding that past it will cease to have happened. Is that it?
The point is more "the past as you see it is created by your understanding", in a few years, you might not remember this night well or at all, have a twisted memory blending other pub nights, have interpreted some interactions with your friends in a different way that they did etc...
The point is more "the past as you see it is created by your understanding", in a few years, you might not remember this night well or at all, have a twisted memory blending other pub nights, have interpreted some interactions with your friends in a different way that they did etc...