After enough time has gone by, reading your own software takes on an interesting aspect. You are rediscovering things that you created years ago, but now you are looking with fresh eyes.
One odd thing about the process is that even though the person who wrote the code is yourself, there is a part of you that feels separate from them. After all, you are thinking about very different things now, whereas they are completely immersed in the thing they are creating.
So it can feel like a sort of collaboration with yourself. In essence you are doing a code review of somebody’s computer program, except the person whose code you are reviewing is you.