On Personal Libraries and Book Collecting

I visited a used bookstore in Oxford yesterday.  While I worked assiduously to fight off my desire to buy the whole shop, I came away with a nice collection of old, hardcover books: Hannah Arendt’s The Human Condition; Walter Lippmann’s The Good Society; and Edmund Burke’s Reflections on the Revolution in France, to name a few.  Upon returning to my flat, I made room for these new purchases on my bookshelf and realized just how elated I was with them.  It is manifest that I love books; yet, this experience was different.  What was it about a used bookstore that augmented my experience of purchasing books for my personal library?