The thing about memories is that you only really properly keep the ones that you look at a lot, as if they were photographs in an album that starts disintegrating if it isn’t opened regularly. The more often you look at a memory, the more vivid it is and the closer it seems, creating a distortion in our perception of time that makes a forgettable yesterday seem more distant than last year’s momentous events.
Despite all this, even looking at a memory once distorts it - synapses fire slightly differently and alter the shape of a building or the sound of someone’s voice. And so those oft-viewed vivid ideas morph into a collage of then and now, and all that’s come between, and things that are entirely separate and other things that never happened at all. So that when you do return to a person, a place, an object, after a long time, the dimensions and details are out of sync and catch you by surprise.