Oh, right, September 11, that rings a bell. That's the day when something unexpected happened. Doesn't really matter what that something was, compared to the lessons to be observed about when the unexpected happens. Because the habitual total routine machinery of life is a big reason people can go on thinking they know something, when in fact they are clueless.
But in a blog about Jan Cox, really, what jumps to mind is the incident I recall where he said to the group of people he had allowed to stay around, "if you leave the group, I will not again think of you." (words to that effect.) One person hearing this, thought, wow, that's cold.
How wrong I was, and whatever I later learned, one thing is this (and contra the many statements you will hear on the media today about never forgetting) you can only remember by not thinking of something.