I have just caught a chap in the back room who had piled up and moved lots of books so that he could create a writing suface on top of a 3 shelf bookcase. He then started to make copious notes on Roman and Norman coins from one of my nicer Numismatics books.
When i asked if i could help him, he replied "Oh no, I've found what I need. I don't want to buy it, I just want to make notes on some coins I have just got."
Should I grab him by his lapels and fling him bodily into the street before jumping up and down on him shouting "curses on your coins you cheapskate, book borrowing, odourous person" or should i just let him carry on using me as a library reference room ?
I am willing to concede that there may be a middle path !