A psychologist writes:

Your Boris moments are examples of a frequently experienced symptom of bereavement. The classic study is by Rees (1971). He found that 14% of widows reported visual hallucination of their husbands, and that 13% reported auditory hallucinations (e.g. hearing his voice). Almost 50% reported “experiencing the presence” of the deceased. Grimby (1993) found that about one-third of elderly bereaved persons saw, heard, and/or spoke to their deceased loved ones.
Technically, these are hallucinations (i.e. creations of the mind), and not illusions, which are distortions of external stimuli. I suppose your “trick of the light” might make the sliding door Boris an illusion, but a Boris-like object would have to be part of the picture. The classic example of an illusion is seeing a person standing in your bedroom at night and then realizing that it is just your trousers thrown over your chair.
I won’t try your patience with a psychodynamic explanation of this phenomenom. I do note, however, that you characterized Mr. Obama as “neurotic” in your March Diary. Creeping Freudianism?

[Me] I’m not sure why it should be creeping Freudianism. Neuroticism is one of the Big Five dimensions in a widely- (though not universally-) accepted theory of human personality structure. I am obliged to my reader, though, for such a clear exposition of the difference between hallucinations and illusions. This is all good prep for my trip to Tucson next week in pursuit of the elusive I.