Me and my Shadow

My therapist is really good.  I think I've found my problem.  It's brought back a memory of an excellent short story that I read years and years ago by Jeff Noon.  It resonated with me back then, which seems to suggest that the problem that has now been identified has been my problem for a good many years:  I have a shadow.

Full disclosure:  I've had a bad week, and wrote most of this post while at work, for reasons which will become clear.