"It wasn't the fault of the people at the cocktail party that the name Anna Magnani meant nothing to them. It was my fault for not having realized it before embarking on a story that was of no interest and made no sense whatsoever!" - Coalport
I dont think you are alone on this! - I couldnt count the number of times I have listened to someone who is usually interesting tell a story and not know what the hell they were talking about!
I think, as you imply, it comes down to assumptions - Assumptions about our "shared" world.. the idea that some person/s events which for us were fairly major, will have registered on the consciousness of others.
For me, this most manifests itself if I talk about South Africa - People I knew, who were (or rather, became) famous - Joe Slovo for example, is someone nobody (or few) here remembers - Desmond Tutu and Steve Biko are probably the only ones I could talk about with anyone knowing who I was talking about... It is only when in the company of other SA exiles that we have a common collective world and can talk of the old days without having to explain who we are talking about - and it must be the mid '80s since I was last with such a group at the last meeting of the exiled South Africa Communist Party held in London...
And I have not kept contact with them - like many others, we were bound by a cause - when the goal was achieved (or at least when we believed it had been achieved) our primary reason for gathering evaporated - And as much of our "shared world" was not a place we enjoyed visiting, well ...
We all have our seperate little worlds - and the passage of time seems to move these worlds further apart.
Regarding your master class - I think there may be a difference.. it may have "served no good purpose" - but I dont see that it could have served a "bad purpose" or have had any "bad" concequences. I am inclined to publish anything which may serve a "useful" purpose - even if this is only useful to a few individuals - provided it doesnt risk causing damage.. The problem is that we need wisdom to weigh up possible concequences.. wisdom we cannot possibly posess
Fred.