Every now and then I notice a gap in my bookshelf - Volume 5 of Winston Churchill's epic, 'The Second World War'.
One volume of a barely read series on my bookshelf is not there, and sadly that bothers me. His entire series on 'World War One' isn't there at all. There are a few other gaps which only a Bodleian sized Library could fill, and that's before you touch on archives and primary sources of 'history'.