I spent the day tiding the Philosophy Shelves; there is a selection above, with lots more on Ethics and other subjects on the website. Tidying a bookcase can be an enjoyable thing but for booksellers it is a frequent necessity. For secondhand booksellers in particular you can suddenly have an influx of new stock in what was previously a category of just a dozen or so items. Space has to be made. Equally you can suddenly sell a lot of books leaving gaps - the gaps are never where you need them!
Both things, buying and selling in quantity are a tremendous pleasure. Buying books? Well unpacking a few hundred books feels like Christmas every time, even though I know I'm only their temporary owner. And selling? It is the Christmas pleasure in reverse - how great to pass books on, however much I'll miss them, to someone who appreciates them.